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UNIVERSITY  OF  MASSACHUSETTS 
LIBRARY 


D 

1915 
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'nsecfary  ; 


Co/;eae. 


ON  SOME  GENERA 

OF  THE 

PIMPLINE  ICHNEUMONIDAE 

by 

J.  H.  Merrill,  Ph.D. 


From  the  Transactions  of  the  American  Entomological  Society,  xli,  109-154 

Issued  May  24.  1915. 


IIBRARY 

h  ■CHUSETTS 
AM  uIt,  MASS. 


J.  H.  MERRILL 


109 


ON  SOME  GENERA  OF  THE  PIMPLINE  .  \ 
ICHNEUMONIDAE 

by  j.  h.  merrill,  ph.d.  ^  •     \.  \ 

Introduction 

This  paper  is  the  result  of  three  years'  work  done  at  the  Massa^- 
chusetts  Agricultural  College  as  a  partial  requirement  for  the 
degree  of  Doctor  of  Philosophy. 

I  wish  to  acknowledge  my  obligations  to  Dr.  H.  T.  Fernald, 
under  whose  direction  this  work  was  carried  on,  to  C.  H.  Fernald 
for  his  kindly  suggestions,  to  Dr.  G.  C.  Crampton  for  valuable 
advice  and  criticism,  to  W.  S.  Regan  for  the  valuable  assistance 
rendered  me  by  securing  specimens  for  study  from  the  museums 
at  Philadelphia,  Washington,  and  New  York,  and  making  notes 
on  the  comparisons  of  these  insects  with  their  types,  and  to  Dr. 
C.  Gordon  Hewitt  for  the  loan  of  a  large  number  of  specimens. 

Mr.  F.  A.  Johnston  began  work  on  this  group  and  had  brought 
together  copies  of  the  descriptions  of  nearly  all  the  insects  treated 
here,  when  he  accepted  a  position  with  the  Bureau  of  Entomology, 
and  the  subject  was  given  to  me  to  continue. 

Fourteen  species  and  four  genera  are  treated  here.  Of  these, 
one  genus  and  one  species  are  described  for  the  first  time.  Most 
of  the  other  North  American  species  are  redescribed,  wherever  it 
was  possible  to  obtain  specimens  from  which  to  make  the  descrip- 
tions. The  genus  Epirhyssa  has  been  abandoned,  as  it  did  not 
seem  to  have  enough  distinctive  generic  characteristics  to  sepa- 
rate it  from  Rhyssa.  A  new  genus  Pseudorhyssa  has  been  estab- 
lished. Its  transversely  wrinkled  mesonotum  places  it  within 
the  scope  of  the  genera  treated  here;  the  entire  sternal  plates 
of  its  abdomen,  however,  separate  it  from  the  other  genera. 
The  type  of  this  genus,  Pseudorhyssa  sternata  is  here  described. 
The  description  of  Thalessa  histrio,  an  unlocated  species,  is  also 
included. 

Probably  the  largest  and  most  valuable  collection  in  this 
country  of  the  insects  treated  here  is  at  the  Academy  of  Natural 

^  Contribution  from  the  Entomological  Laboratory  of  the  Massachusetts 
Agricultural  College,  Amherst,  Mass. 

TRANS.  AM.  ENT.  SOC,  XLI. 


110 


PIMPLINE  ICHNEUMONIDAE 


Sciences  in  Philadelphia.  Other  collections  from  which  material 
used  in  the  preparation  of  this  paper  was  borrowed,  were  those 
at  the  National  Museum  in  Washington,  the  American  Museum 
in  New  York,  the  Museum  of  the  Boston  Society  of  Natural 
History  in  Boston,  the  Children's  Museum  in  Brooklyn  and  the 
collection  of  the  Dominion  Entomologist  of  Canada.  The 
collections  at  the  Museum  of  the  Academy  of  Natural  Sciences 
of  Philadelphia  and  the  National  Museum  in  Washington  are 
especially  valuable,  in  that  a  number  of  type  specimens  are 
located  there. 

Historical 

Linnaeus  was  the  first  to  describe  insects  in  this  group.  From 
his  time  down  to  the  present,  there  have  been  numerous  workers, 
but  beyond  synoptic  tables  to  the  genera,  they  have  done 
nothing  except  to  describe  some  of  the  species. 

Holmgren  2  called  the  genus  Megarhyssa,  Thalessa,  in  1859, 
but  Adams  had  used  this  name  in  1858  for  a  genus  of  mollusks. 
Ashmead^  proposed  the  name  Megarhyssa  on  account  of  the 
name  Thalessa  being  preoccupied  in  another  branch  of  zoology. 
Dalla  Torre ^  places  '^non  Adams  1858"  after  the  reference  to 
Ashmead;  this  should  have  been  placed  after  the  reference  to 
Holmgren. 

The  chief  workers  in  this  group  have  been  Linnaeus,  Fabricius, 
Kriechbaumer,  Cameron,  Cresson  and  Viereck.  Both  Cresson 
and  Kriechbaumer  not  only  described  and  named  several  new 
species  but  each  established  a  new  genus. 

In  the  Proceedings  of  the  United  States  National  Museum 
for  1901,  vol.  xxiii,  Ashmead  divides  the  sub-family  Pimplinae 
into  tribes  and  establishes  among  others  the  tribe  Pimplini. 
Up  to  this  point  his  synoptic  tables  may  be  made  use  of,  but 
when  it  is  desired  to  determine  the  genera  treated  here  it  will 
be  necessary  to  use  a  new  key,  because  other  generic  values 
have  been  given  to  some  characters,  while  the  value  of  others 
has  been  lessened.  The  62nd  fascicle  of  the  Genera  Insectorum 
uses  a  key  similar  to  the  one  used  by  Ashmead  and  the  same 
criticism  applies  to  it.    In  Cresson's  Synopsis  of  the  Hymen- 

-  Ofvers.  Svensk.  Vet.-Akad.  Forh.,  xvi,  1859,  p.  122. 
2  Canadian  Entomologist,  xxxii,  1900,  p.  368. 
^  Catalogus  Hymenopterorum,  viii,  p.  479. 


J.   H.  MERRILL 


111 


optera,  no  division  of  the  sub-family  is  attempted  but  the  key 
is  similar  to  the  two  preceding  ones  in  the  generic  characters  used. 

The  genus  Megarhyssa  is  fairly  constant  in  both  color  and 
structural  characteristics,  while  the  genus  Rhyssa  exhibits  con- 
siderable variation  in  both.  For  that  reason  it  would  seem  unsafe 
to  describe  a  new  species  from  a  single  specimen  in  Rhyssa. 

External  Anatomy 

The  following  description  is  taken  mainly  from  Megarhyssa 
lu7iator.  Certain  modifications  have  been  made  to  describe 
such  differences  as  may  occur  in  different  species  of  the  group 
treated  here. 

Head 

The  head  is  hypognathous,  broader  than  long.  Its  general 
shape  when  viewed  from  in  front  is  rounded-triangular.  The 
compound  eyes  are  large,  extending  from  the  top  of  the  head  to 
the  clypeus.  They  are  broad,  together  constituting  one-half 
the  width  of  the  head  when  viewed  from  in  front  and  when  viewed 
from  the  side,  at  their  widest  part,  forming  a  little  more  than 
half  the  width  of  the  head.  The  inner  margins  of  the  compound 
eyes  are  slightly  emarginated  on  its  upper  third,  but  nearly 
form  two  parallel  lines  with  each  other.  The  posterior  margins 
are  entire.    The  eyes  are  naked. 

The  clypeus  occupies  the  lower  portion  of  the  front  of  the  head 
and  extends  up  to  the  lower  borders  of  the  compound  eyes. 
The  clypeus  is  narrow  and  elongated  transversely.  Laterally 
below  the  eyes  it  has  fused  with  the  cheeks.  There  is  an  impres- 
sion reaching  from  the  eyes  to  about  the  middle  of  the  mandibles 
which  suggests  that  it  was  a  suture  marking  the  division  between 
the  clypeus  and  the  cheeks.  If  this  is  true,  then  the  clypeus 
and  cheeks  together  form  the  basal  support  of  the  mandibles. 
The  lower  border  of  the  clypeus  between  the  mandibles  varies 
in  outline,  in  different  genera,  from  concave  to  convex.  This 
fact  is  made  use  of  in  the  determination  of  genera. 

The  frons,  vertex,  occiput  and  upper  ends  of  the  genae  are 
fused,  but  the  occiput  and  genae  are  fused  dorsally,  while  later- 
ally they  are  separated  by  a  suture,  and  ventrally  by  a  ridge. 
The  occiput  may  be  considered  as  that  portion  of  the  back  of 
the  head  which  is  nearly  vertical.  It  is  concave  from  side  to 
side,  and  the  prothorax  attaches  at  about  its  center. 

TRANS.  AM.  ENT.  SOC,  XLI. 


112 


PIMPLINE  ICHNEUMONIDAE 


The  lack  of  definite  sutures  separating  the  plates  of  the  head, 
necessitates  the  establishment  of  artificial  boundaries.  The 
vertex  will  be  considered  as  extending  from  a  line  drawn  through 
the  posterior  ocelli,  back  to  a  line  from  the  ends  of  the  sutures 
separating  the  genae  from  the  occiput.  The  lateral  limits  of 
the  vertex  can  be  definitely  fixed,  but  will  be  considered  as 
extending  to  the  compound  eyes. 

The  portion  of  the  head  behind  the  compound  eyes,  extending 
from  the  vertex  to  the  clypeus  and  back  to  the  occiput,  will 
be  considered  as  the  genae.  The  greatest  width  of  the  genae 
is  at  the  lower  border  of  the  compound  eyes.  They  gradually 
become  narrower  towards  the  top  of  the  head. 

The  labrum  is  attached  to  the  clypeus  between  the  front 
borders  of  the  mandibles.  Being  attached  to  the  lower  and 
inner  side  of  the  clypeus,  it  leaves  the  anterior  borders  of  the 
latter  clearly  defined.  The  labrum  bears  a  thick  row  of  long 
spines  on  its  outer  edge. 

The  mandibles  are  situated  on  either  side  of  the  labrum. 
They  are  broad  at  the  base,  taper  gradually  toward  the  apex 
and  the  tip  is  slightly  incurved.  They  have  two  teeth,  the 
anterior  one  being  blunt,  while  the  posterior  one  is  produced 
to  a  point.  The  maxillae  lie  behind  the  mandibles  and  each 
has  a  five-segmented  palpus.  The  labium  is  so  well  concealed 
by  the  maxillae  that  it  was  impossible  to  separate  it  for  careful 
study  in  the  time  at  my  disposal. 

The  antennae  are  filiform,  long,  slender  and  composed  of  about 
forty  segments.  They  are  covered  by  a  large  number  of  minute 
spines.  The  main  portion  of  the  scape  is  bluntly  spindle-shaped 
when  viewed  from  the  mid  line  of  the  body,  or  from  somewhat 
below  the  point  of  attachment.  From  this  angle,  the  fact  that 
the  upper,  outer  side  of  this  spindle  has  quite  a  deep,  oval  exca- 
vation from  which  the  pedicel  arises,  is  not  perceptible.  At 
its  widest  part,  the  scape  is  about  twice  as  wide  as  the  other 
segments.  The  bulb  below  the  constriction  enlarges  so  that 
its  outline  is  triangular.  The  first  segment  of  the  antenna  is 
globular  and  very  much  differentiated  from  the  others.  It  is 
broader  than  long  and  about  one-fifth  the  length  of  the  second 
segment.  The  remaining  segments  are  cylindrical  and  a  gradual 
decrease  in  size  appears  on  the  outer  half  of  the  antenna.  The 


J.  H.  MERRILL  113 

last  segment  is  nearly  twice  as  long  as  the  preceding  segment 
and  narrows  rather  suddenly  towards  the  tip. 

Thorax 

The  prothorax  consists  of  four  visible  plates;  the  notum,  two 
episterna,  and  a  sternum.  Each  episternum  (Eps.i)  at  its  an- 
terior end,  articulates  with  the  head  by  a  hooked  process  which 
is  the  remains  of  the  cervical  sclerite.  The  episterna  are  sepa- 
rated ventrally  by  a  median  longitudinal  suture.  At  the  point 
of  articulation  with  the  head,  each  is  quite  slender,  but  posteriorly 
it  enlarges  and  flattens  out  into  a  lobe  which  passes  downward 
and  backward  below  the  pronotum  and  articulates  at  its  posterior 
end  with  the  procoxa  (Cx.i)  of  an  anterior  leg.  As  in  most 
Hymenoptera,  the  episternum  constitutes  the  greater  part  of 
the  pleural  portion  of  the  prothorax,  the  epimeron  being  reduced 
to  a  strip  so  narrow  that  it  is  almost  negligible,  on  the  posterior 
border  of  the  episternum  and  is  hidden  under  the  pronotum. 

The  pronotum  (N.i)  is  very  broad  laterally,  its  anterior  face, 
being  narrowed,  forms  a  connection  between  the  lateral  plates. 
The  sides  are  highly  polished.  The  pronotum  reaches  the  base 
of  the  tegulae  (Tg.)  and  is  produced  downward  to  the  episternum, 
coxae  and  sternum  ventrally.  The  pronotal  lobe  (Pnl.)  is  dis- 
tinct, though  small,  forming  a  peritremal  sclerite  overlapping 
the  first  thoracic  spiracle  (Tsp.).  The  sternum  is  overlapped 
and  largely  concealed  by  the  approximated  lobes  of  the  episterna. 

In  the  mesonotum,  the  prescutum,  scutum  and  scutellum  are 
plainly  distinguishable.  The  postscutellum  is  small  and  for 
the  most  part  is  a  phragma  or  internal  process. 

Near  the  upper,  posterior  corner  of  the  pronotum,  on  each 
side  and  just  below  the  anterior  end  of  the  attachment  of  the 
fore  wing  to  the  body  is  the  first  thoracic  spiracle  (Tsp.). 

The  prescutum  (Psc.2)  is  a  triangular  shaped  plate,  above-  the 
pronotum  and  separated  from  the  scutum  by  two  sutures  which 
posteriorly  converge  and  become  transformed  into  flattened 
grooves.  The  front  portion  of  the  prescutum  is  nearly  vertical 
and  forms  almost  a  right  angle  with  its  hinder  portion,  when 
viewed  from  the  side. 

Medially,  the  scutum  (Sct.2)  extends  to  the  raised  median 
portion  of  the  scutellum.    Posteriorly  the  scutum  is  sunken 

TRANS.  AM.  ENT.  SOC,  XLI. 


114 


PIMPLINE  ICHNEUMONIDAE 


between  the  lateral  plates  of  the  scutellum  (Scl.2),  so  that  its 
lateral  margins  are  concealed.  Both  the  prescutum  and  scutum 
are  transversely  rugose.  The  lateral  margin  of  the  prescutum 
is  deflexed.  The  anterior  portion  of  this  deflexed  margin  is 
overlapped  by  the  dorsal  border  of  the  pronotum.  From  the 
top  of  the  pronotal  lobe,  just  above  the  first  thoracic  spiracle, 
is  a  ridge  extending  to  the  anterior  corner  of  the  lateral  lobe 
of  the  scutellum,  behind  which  point,  the  margin  of  the  scutum 
is  concealed  by  this  lobe,  as  already  stated.  Below  and  behind 
this  ridge,  the  scutum  bends  abruptly  and  is  somewhat  hollowed, 
the  lower  margin  of  this  portion  of  the  plate  extending  backward 
until  opposite  the  front  end  of  the  lateral  lobe  of  the  scutellum. 
The  margin  now  turns  upward  and  forms  a  suture  with  the  front 
margin  of  the  lateral  lobe  of  the  scutellum. 

The  scutellum  (Scl.2)  consists  of  a  median  raised  portion  and 
two  deflexed  regions.  From  the  front  of  the  median  portion  of 
the  scutellum  a  ridge  runs  downward  on  the  side  of  the  body 
toward  the  lower,  hinder  angle  of  the  plate,  and  may  be  considered 
as  marking  the  line  between  the  median  portion  and  the  lateral 
lobe.  The  lateral  lobe,  as  thus  indicated,  is  approximately 
rectangular,  its  lower,  hinder  angle  being  somewhat  drawn  out 
and  its  lower  border  somewhat  emarginated.  The  hinder  margin 
of  the  median  portion  of  the  scutellum  is  practically  a  straight 
line,  running  obliquely  backward  on  either  side. 

The  fore  wing  has  a  much  elongated  attachment  to  the  body, 
its  humeral  angle  appearing  just  behind  the  pronotal  lobe,  and 
its  internal  margin  near  the  lower,  posterior  corner  of  the  lateral 
lobe  of  the  scutellum.  Beneath  this  wing  attachment  lies  the 
upper  margin  of  the  mesoepisternum  (Eps.2). 

The  tegula  (Tg.)  which  lies  over  the  anterior  portion  of  the 
base  of  the  wing  is  a  small  chitinous  plate,  which  appears  to  be 
attached  medially  to  the  front  end  of  the  hollowed  portion  of  the 
scutum,  just  below  the  front  edge  of  the  ridge  already  described. 
Its  real  attachment  and  relation  to  the  wing  are  considered  under 
a  separate  heading  elsewhere  in  this  paper.  Two  tiny  basal  wing 
sclerites  lie  beneath  the  costal  and  anal  regions  of  the  wing. 

As  in  the  prothorax,  the  episternum  (Eps.2)  constitutes  the 
greater  part  of  the  pleural  region.  It  is  fused  with  the  sternum 
(S.)  which  has  a  narrow,  deep,  mid-ventral  groove  extending 


J.  H.  MERRILL 


115 


longitudinally  throughout  its  whole  length.  On  the  episternum, 
a  short  distance  behind  its  front  margin,  is  a  nearly  vertical 
suture  extending  about  half  way  up  to  the  dorsal  margin  of  the 
plate,  crossing  it  beneath  and  continuous  with  the  corresponding 
suture  of  the  other  side,  separating  the  lower,  anterior  portion  of 
each  episternum  from  the  remainder.  This  portion  is  called  the 
prepectus  (Ppct.2).  The  epimeron  (Epm.2)  is  a  narrow  band 
separated  from  the  episternum  by  a  suture  extending  in  a  straight 
line  from  the  hinder  base  of  the  fore  wing  downward  and  back- 
ward to  the  mesocoxa  (Cx.2).  The  sternal  area  is  flat  beneath, 
punctured  and  sometimes  striated. 

The  distinguishable  plates  of  the  metanotum  are  the  scutum, 
scutellum  and  postscutellum.  The  region  here  called  metanotum 
is  the  one  which  has  been  usually  termed  the  postscutellum  of 
the  mesothorax  by  the  systematists.  The  metascutum  (Set. 2) 
lies  immediately  behind  the  scutellum  of  the  mesothorax.  Its 
narrow  dorsal  surface  is  sunken  below  the  surfaces  of  both  the 
mesoscutellum  and  the  metascutellum.  Laterally  it  consists  of 
two  deflexed  regions.  The  hind  wings  are  dorsally  attached 
by  a  membrane,  to  the  scutum,  and  behind  and  below  are  simi- 
larly attached  by  a  forward  projecting  process  of  the  metapleuron. 
In  the  anal  and  humeral  angles  are  borne  the  small,  sub-alar 
basal  wing  sclerites.  The  scutellum  (Scl.3)  consists  of  a  raised 
median  portion.  Immediately  posterior  to  the  scutellum  lies 
the  postscutellum  (Pscl.3)  which  is  a  sunken,  narrow,  transverse 
bank-like  region  fusing  laterally  with  the  metaepimeron. 

The  pleurum  consists  of  an  episternal  and  epimeral  region, 
of  which  the  former  is  much  the  larger.  That  portion  of  the 
pleurum  which  is  fused  with  the  metapostscutellum  is  epimeral 
(Epm.3).  The  suture  which  separates  the  epimeron  from  the 
first  abdominal  segment  becomes  lost  for  most  of  the  distance 
along  the  ventral  margin  of  the  latter  segment,  reappearing 
again  for  a  short  distance  at  its  hinder,  ventral  portion.  The 
main  part  of  the  episternum  (Eps.3)  lies  beneath  the  metae- 
pimeron and  its  hinder  margin  articulates  with  the  metacoxa 
(Cx.3).  The  upper,  anterior  corner  is  prolonged  into  a  narrow 
bank-like  region  lying  between  the  mesoepimeron  and  the  fused 
metapostscutellum,  and  metaepimeron.  It  is  separated  from 
each  by  sutures.    The  pleura  are  fused  with  the  sternum  which 

TRANS.  AM,  ENT.  SOC,  XLI. 


116 


PIMPLINE  ICHNEUMONIDAE 


is  marked  by  a  longitudinal  mid-ventral  groove,  as  in  the  meso- 
thorax,  and  is  continuous  with  it. 

Wings 

The  wings  are  long  and  narrow,  quite  large,  usually  hyaline* 
marked  more  or  less  with  dark  spots.  In  some  species  the  wings 
are  entirely  cloudy.  The  fore  and  hind  wings  are  connected 
when  in  flight,  by  a  row  of  frenal  hooks  on  the  hind  wing  hooking 
into  the  frenal  fold  of  the  front  wing. 

In  describing  the  veins  and  cells,  the  terminology  used  by 
Cresson  in  his  '^Synopsis  of  the  Hymenoptera  of  North  America,'' 
will  be  followed  here. 

In  the  fore  wing,  the  costal  and  subcostal  veins  are  blended, 
therefore  the  costal  cell  is  absent.  They  extend  to  a  point  a 
little  beyond  the  middle  of  the  wing,  where  there  is  a  slight 
notch  in  the  costa.  From  this  notch,  to  a  point  about  half 
way  from  it  to  the  apex,  is  a  thickened,  darker  strip  which  may 
be  regarded  as  the  stigma.  Behind  the  blended  costa  and  sub- 
costa,  lie  the  externo-medial  and  anal  nervures.  The  externo- 
medial  nervure  at  its  outer  end,  meets  the  basal  nerve  obliquely; 
this  basal  nervure  joins  the  subcosta  at  a  point  a  little  before  the 
stigma.  The  cell  outlined  by  these  nervures  is  called  the  sub- 
median  or  interno-medial  cell.  The  anal  nervure  lies  behind 
the  externo-medial  nervure  and  extends  outward  until  it  joins 
the  anal  margin  at  a  point  nearly  two-thirds  the  length  of  the 
wing  from  the  base.  At  the  junction  of  the  basal  nervure  with 
the  externo-medial  nervure,  the  transverse-medial  nervure 
extends  at  nearly  a  right  angle  with  the  latter,  to  the  anal  nerv- 
ure; thus  outlining  the  sub-median  or  interno-medial  cell. 
Behind  the  anal  vein  and  in  front  of  the  anal  margin  lies  the 
long,  narrow,  anal  cell.  The  marginal  or  radial  nervure  appar- 
ently arises  from  the  hinder  edge  of  the  stigma  and  extends 
toward  the  apex,  but  before  reaching  it,  turns  -forward  to  the 
front  margin,  thus  enclosing  the  marginal  or  radial  cell.  The 
discoidal  nervure  extends  from  the  junction  of  the  externo- 
medial,  basal,  and  transverse-medial  nervures,  outward  until 
it  joins  the  cubital  nervure,  where  it  bends  abruptly  backward 
and  joins  the  anal  nervure  just  before  the  latter  reaches  the  anal 
margin.    The  cell  outlined  by  the  transverse-medial  nervure 


J.  H.  MERRILL 


117 


on  its  inner  margin,  the  discoidal  nervure  on  its  front  and  outer 
margins,  and  the  anal  nervure  on  its  hinder  margin,  is  the  second 
discoidal  cell.  The  cubital  nervure  extends  outward  from  the 
point  where  the  discoidal  nervure  bends  abruptly  backward,  and 
becomes  lost  a  short  distance  before  the  outer  margin.  About 
the  middle  of  the  marginal  nervure  arises  a  cross  nervure  which 
passes  backward  and  joins  the  cubital  at  about  its  middle.  This 
nervure  has  been  termed  the  first  transverse  cubital,  and  forms 
the  outer  margin  of  the  very  large,  somewhat  triangular  cell 
lying  behind  the  base  of  the  stigma,  called  ♦the  cubito-discoidal 
cell.  A  short  stump  of  a  nervure  projecting  from  the  cubital 
into  the  cubito-discoidal  cell  is  called  by  Cresson  an  ''abbreviated 
cubital  nervure."  The  real  significance  of  this  nervure  will  be 
discussed  later.  A  short  distance  external  to  the  first  transverse 
cubital  is  another  cross  nervure,  the  second  transverse  cubital. 
The  relation  of  these  two  nervures  differs  greatly,  their  anterior 
ends  may  be  close  together  on  the  marginal  nervure,  while  their 
posterior  ends  are  some  distance  apart.  These  nervures  enclose 
the  areolet  or  second  submarginal  cell.  In  some  cases,  the  anterior 
ends  of  the  two  transverse-cubital  nervures  are  united  for  about 
half  their  length.  In  this  case,  the  areolet  is  said  to  be  petio- 
lated.  Occasionally,  the  second  transverse  cubital  is  lost  or 
reduced  to  an  abbreviated  stub,  in  which  case,  the  areolet  is 
absent.  The  presence  or  absence  of  an  areolet  which  has  here- 
tofore been  used  as  a  generic  character,  is  not  even  a  specific 
one,  as  both  conditions  have  been  found  to  occur  in  the  same 
species. 

The  second  transverse  cubital  nervure  forms  the  inner  margin 
of  the  third  submarginal  cell  which  extends  outward  to  the  outer 
margin  of  the  wing."  Its  front  border  is  formed  by  the  outer 
half  of  the  marginal  or  radial  nervure,  and  its  hinder  border 
by  the  outer  portion  of  the  cubital  nervures.  Between  the 
cubital  nervure  and  the  internal  margin  of  the  wing,  extending 
nearly  to  the  outer  margin  from  about  the  middle  of  the  back- 
wardly  turned  portion  of  the  discoidal  nervure,  is  the  subdiscoidal 
nervure.  That  portion  of  the  discoidal  nervure  between  the 
cubital  and  subdiscoidal  nervures  is  the  first  recurrent  nervure, 
according  to  Cresson,  though  here  described  as  part  of  the  dis- 
coidal.   The  second  recurrent  is  a  somewhat  curved  nervure 

TRANS.  AM.  ENT.  SOC,  XLI, 


118 


PIMPLINE  ICHNEUMONIDAE 


extending  backward  from  the  middle  of  the  areolet  to  near 
the  outer  end  of  the  subdiscoidal.  The  recurrent  nervures 
form  the  inner  and  outer  margin  of  the  third  discoidal  cell,  with 
the  cubital  forming  its  front  and  the  subdiscoidal  joining 
its  hinder  borders.  The  subdiscoidal  nervure  forms  the  front 
margin  of  the  first  apical  cell,  while  its  inner  margin  is  formed 
by  the  outer  part  of  the  discoidal  nervure  and  behind  it  is  bounded 
by  a  small  portion  of  the  anal  nervure,  the  outer  part  of  the 
internal  margin,  the  anal  angle  and  the  hinder  portion  of  the 
outer  margin  of  the  wing.  Between  the  cubital  and  subdiscoidal 
nervures  and  extending  from  the  second  recurrent  nervure  to 
the  outer  margin,  lies  the  second  apical  cell.  The  f renal  fold 
is  near  the  outer  end  of  the  anal  cell. 

The  writer  is  inclined  to  agree  with  Snodgrass^  in  his  inter- 
pretation of  the  venation  of  an  Ichneumonid  wing,  as  indicated 
by  his  Figure  76,  rather  than  with  that  used  by  Cresson.^ 

The  two  systems  agree  in  the  main,  the  points  of  disagreement 
being  the  discoidal  and  first  recurrent  nervures.  According  to 
the  system  used  by  Cresson,  the  first  recurrent  nervure  (1.)  sep- 
arates the  two  parts  of  the  discoidal  nervure  (j.). 

In  the  fore  wing  of  Mellinus  which  Cresson^  uses  as  a  typical 
Hymenopteron  wing,  the  two  recurrent  nervures  are  very  distinct 
and  there  can  be  no  question  raised  as  to  their  identity.  Here, 
the  first  recurrent  nervure  extends  from  the  discoidal  nervure 
(j.)  to  the  cubital  nervure  (k.).  In  the  fore  wing  of  Megarhyssa 
lunator,  the  cubital  nervure  at  its  anterior  end  is  but  an  abbre- 
viated stump.  According  to  Snodgrass,  the  vein  from  (j.)  to 
(k.)  forms  the  first  recurrent  nervure  (No.  16,  fig.  76).  This  agrees 
with  the  condition  found  in  Mellinus  and  seems  to  be  a  more 
plausible  explanation  than  calling  it  part  of  the  discoidal  nervure 
(1.)  with  parts  of  the  latter  on  either  side  of  it  (j.).  If  Snod- 
grass's  interpretation  is  accepted,  then  the  discoidal  nervure 
remains  as  such  from  beginning  to  end. 

In  Mellinus  the  first  transverse  cubital  nervure  extends  for- 
ward from  the  point  where  the  first  recurrent  nervure  joins  the 
cubital,  to  the  marginal  or  radial  nervure,  but  in  the  fore  wing 

5  'Thorax  of  Hymenoptera,'  1910,  pi.  6,  fig.  76. 

^  Synopsis  of  the  Hymenoptera  of  North  America,  p.  38,  fig.  9. 

^  Synopsis  of  the  Hymenoptera  of  North  America,  p.  5,  fig.  4. 


J.  H.  MERRILL 


119 


of  Megarhyssa  lunator,  the  transverse  cubital  nervure  is  lost. 
As  a  result  of  this,  the  so-called  cubito-discoidal  cell  includes 
not  only  the  first,  but  the  second  cubital  cell,  and  the  cells  spoken 
of  by  Cresson  as  the  second  and  third  cubital  cells  are  in  reality 
the  third  and  fourth  cubital  cells.  The  nervures  (f.)  and  (g.) 
though  called  the  first  and  second  transverse  cubitals  are  actually 
the  second  and  third. 

In  the  hind  wing  the  nervures  and  cells  are  fewer  in  number 
than  in  the  fore  wing.  The  subcostal  nervure  runs  outward 
from  the  base  of  the  wing  for  nearly  two-thirds  the  length  of 
the  latter,  joining  the  costa  at  a  small  notch  in  the' costal  margin. 
From  this  point  the  radial  or  marginal  nervure  passes  obliquely 
outward  and  backward  to  the  outer  margin  some  little  distance 
behind  the  apex.  Behind  the  subcostal  lies  the  externo-medial 
nervure,  which  passes  outward,  gradually  diverging  from  the 
former  till  intersected  by  two  cross  nervures.  Beyond  the  inter- 
section it  continues  to  the  hinder  margin,  this  portion  being 
termed  the  discoidal  nervure.  Behind  the  externo-medial 
nervure  is  a  third  longitudinal  nervure  which  extends  from  the 
base  of  the  wing  to  its  hinder  margin,  which  it  reaches  a  short 
distance  before  the  middle  of  the  margin.  The  externo-medial 
nervure  is  intersected  in  front  by  the  cubital  nervure,  the  two 
uniting  at  nearly  right  angles.  The  latter  abruptly  turns  out- 
ward, however,  and  gradually  backward  and  reaches  the  hinder 
margin  of  the  wing  about  half  way  between  the  ends  of  the  dis- 
coidal and  marginal  nervures.  At  about  its  middle,  it  is  joined 
by  the  hinder  end  of  the  transverse  cubital  nervure  which  passes 
forward,  then  outward,  then  forward  and  unites  with  the  mar- 
ginal nervure  near  its  middle.  From  the  point  of  intersection 
of  the  externo-medial  and  cubital  nervures  the  transverse  medial 
originates,  extending  backward  and  inward  and  joins  the  anal 
nervure  a  short  distance  before  the  latter  reaches  the  wing 
margin. 

The  cell  lying  between  the  costa  and  the  subcostal  nervure  is 
known  as  the  costal  cell:  that  in  front  of  the  marginal  or  radial 
nervure,  as  the  marginal  or  radial  cell:  that  bounded  in  front  by 
the  costal  and  part  of  the  radial  nervures,  behind  by  the  externo- 
medial  and  the  inner  part  of  the  cubital  nervures,  and  externally 
by  the  transverse  cubital  nervure — the  largest  cell  of  the  wing — 

TRANS.  AM.  ENT.  SOC,  XLI. 


120  PIMPLINE  ICHNEUMONIDAE 

» 

is  the  median  cell.  Between  the  outer  parts  of  the  marginal  and 
cubital  nervures,  external  to  the  transverse  cubital  nervure  is 
the  submarginal  or  cubital  cell.  Behind  this,  between  the 
cubital  and  discoidal  nervures  lies  the  first  discoidal  cell.  Be- 
tween the  externo-medial  and  anal  nervures  and  extending  from 
the  base  of  the  wing  to  the  transverse  medial  nervure,  lies  the 
submedian  cell,  external  to  which  and  separated  from  it  by  the 
transverse  medial  nervure  lies  the  second  discoidal  cell.  The 
area  behind  the  anal  nervure  is  known  as  the  anal  cell. 

Legs 

The  legs  are  long  and  slender,  the  coxa  being  the  stoutest 
part  of  each  leg.  The  coxae,  trochanters,  femora  and  tibiae, 
which  are  clothed  with  minute  hairs  or  spines,  are  sometimes 
almost  pubescent.  At  the  outer  end  of  each  tibia  are  two  long 
spines  of  unequal  length,  on  the  sides  towards  the  body.  The 
tarsi  are  covered  with  short  spines  becoming  longer  at  the  end 
of  each  segment. 

On  the  fore  legs,  the  coxae  are  large,  but  are  the  shortest  ones 
of  the  three  sets.  Each  is  sub-conical  in  form,  with  the  tro- 
chanter articulating  at  its  apex.  The  trochanter  is  well  devel- 
oped and  composed  of  two  segments,  the  first  being  the  larger. 
Its  base  is  cylindrical,  but  at  the  tip  of  the  second  section  where 
it  articulates  with  the  femur  it  is  flattened. 

The  fore  femur  is  the  shortest  of  any.  At  its  articulation  with 
the  trochanter,  it  is  flattened  and  for  a  short  distance  it  decreases 
in  width.  It  then  begins  to  widen  and  thicken,  becoming  sub- 
cylindrical  just  before  articulating  with  the  tibia. 

The  fore  tibia  is  the  only  one  which  is  shorter  than  its  femur. 
It  is  narrow  and  cylindrical  at  its  base  of  articulation,  but 
gradually  increases  in  size  to  its  outer  end.  Its  outer  side  is 
clothed  with  short  spines. 

The  tarsus  is  composed  of  five  segments,  all  of  which  are 
cylindrical  and  slightly  enlarged  at  their  outer  ends.  They 
decrease  in  length  from  the  tibia  outward  to  the  fifth  segment 
which  is  slightly  longer  than  the  fourth.  On  that  portion  of 
the  tarsus  overlapped  by  the  tibial  spurs  is  a  raised  area,  which 
together  with  the  latter,  forms  a  cleaning  apparatus.  The 
longest  spines  of  the  tarsus  are  found  at  the  tip  of  the  fourth 


J.  H.  MERRILL 


121 


segment.  At  the  tip  of  the  fifth  is  a  pair  of  strong,  well-developed, 
incurved  claws,  between  which  is  a  large  pul villus. 

The  middle  coxa  is  larger  than  the  fore  coxa  and  is  more  cylin- 
drical than  conical.  The  middle  femur  is  straighter  and  longer 
than  the  fore  femur.  At  its  base  it  is  narrow,  but  soon  broadens 
out  and  remains  the  same  width  for  the  rest  of  its  length.  The 
middle  tibia  is  longer  than  the  fore  tibia  and  also  longer  than 
the  middle  femur.  In  all  other  respects  the  middle  leg  is  like 
the  fore  leg. 

The  hind  legs  are  the  longest  and  in  all  respects  they  resemble 
the  middle  legs  rather  than  the  fore  legs. 

Abdomen 

The  abdomen  consists  of  nine  visible  segments.  It  is  depressed 
behind  the  propodeum  but  towards  the  end  is  mostly  compressed. 
It  has  lateral  impressed  lines  on  segments  three  to  six,  which 
converge  toward  the  middle  of  the  base.  The  abdomen  is  some- 
times finely,  transversely  aciculated.  The  dorsal  portion  is 
coriaceous. 

The  first  segment  of  the  abdomen  is  the  median  segment  or 
propodeum,  and  has  often  been  considered  to  be  part  of  the 
metathorax.  Anteriorly  it  articulates  with  the  metapostscu- 
tellum  and  the  metaepimeron.  The  latter  extends  along  its 
lower  border.  The  sternum  of  this  segment  is  either  lost  or 
has  fused  with  the  metasternum.  The  pleural  elements  have 
fused  with  the  notum  forming  a  single  continuous  plate.  It  is 
usually  smooth,  but  in  some  cases  has  a  channeled  groove  along 
its  mid-dorsal  line  and  may  even  be  areolated.  The  presence 
or  absence  of  these  areolations  is  used  for  generic  distinction. 
On  either  side  it  bears  a  large  spiracle,  these  forming  the  largest 
spiracles  found  in  the  abdomen. 

The  actual  second  segment,  usually  rated  as  the  first  by  sys- 
tematists,  is  constricted  at  its  base,  joining  the  true  first  segment 
or  propodeum  as  by  a  stem.  Its  attachment  is  such  that  it  is 
enabled  to  articulate  freely.  Here  as  in  all  the  rest  of  the  seg- 
ments, the  pleura  are  fused  with  the  notum.  It  is  straight,  with 
its  spiracles  placed  before  the  middle  and  closer  to  each  other 
than  to  the  apical  margin.  These  facts  are  made  use  of  in 
classifying  to  the  tribe.    At  the  base  of  this  segment,  the  fused 

TRANS.  AM.  ENT.  SOC,  XLI. 


122 


PIMPLINE  ICHNEUMONIDAE 


notum  and  pleura  become  fused  with  the  sternum  for  a  greater 
or  lesser  distance.  The  amount  of  this  fusion  is  used  in  classi- 
fication to  species,  and  the  presence  or  absence  of  it  is  made  use 
of  for  generic  distinction.  The  sternum  is  divided  into  an  anterior 
and  a  posterior  portion  by  a  transverse  groove.  The  latter 
portion  is  again  divided  into  two  parts  by  a  longitudinal  mid- 
ventral  groove. 

Considerable  variation  from  the  typical  form  in  regard  to  the 
construction  of  the  sternal  plate  has  been  found.  A  large  part, 
often  as  much  as  half  of  the  posterior  portions  of  this  plate  may 
be  membranous  in  place  of  being  mainly  composed  of  chitin, 
as  is  the  case  in  some  species.  It  is  impossible  to  determine 
whether  this  characteristic  is  the  primitive  condition  or  is  a 
degeneration,  though  the  weight  of  evidence  would  point  towards 
the  latter,  as  the  few  species  possessing  this  modification  are  in 
other  respects  the  most  highly  developed  of  this  group. 

The  third  segment,  like  the  second,  is  truncate  at  its  apex, 
while  the  fourth,  fifth  and  sixth  segments  are  prolonged  laterally 
at  the  apex.  There  is  a  gradual  increase  in  size  in  these  segments, 
otherwise  their  structures  closely  resemble  each  other.  In  each, 
the  notum  and  pleura  are  fused,  but  the  sternum  is  a  separate 
plate.  On  the  pleura  are  laterally  impressed  lines  converging 
toward  the  base.  The  sternal  plates  of  these  segments  are 
separated  by  a  mid-ventral  longitudinal  groove.  On  either  side 
of  this  groove  is  a  small  projection,  the  tips  of  which  point  toward 
each  other.  The  size  and  position  of  these  projections  vary  in 
different  genera.    This  character  is  used  for  generic  classification. 

In  the  female  the  last  three  segments  of  the  abdomen  are 
highly  specialized.  Ventrally  they  are  plow-share  shaped. 
The  seventh  is  the  deepest  segment  of  the  abdomen.  Its  ventral 
plate,  however,  is  very  small.  Between  the  dorsal  portions  of 
the  seventh  and  eighth  segments  is  the  membrane  used  by  the 
female  for  coiling  up  the  ovipositor,  before  thrusting  it  into  the 
tree  in  which  she  desires  to  oviposit.  The  ovipositor  becomes 
external  on  the  ventral  side  between  the  seventh  and  eighth 
segments.  It  is  long  and  slender,  varying  in  length;  in  some 
species  attaining  a  length  of  five  or  six  inches  and  is  always 
longer  than  the  body  of  the  insect.  It  is  composed  of  three 
lateral  sections  which  interlock.    The  ventral  plates  of  the  eighth 


J.  H.  MERRILL 


123 


and  ninth  segments  are  for  the  most  part  membranous.  The 
base  of  the  sheaths  of  the  ovipositor  arises  in  these  ventral 
plates  and  extends  thus  nearly  to  the  apex  of  the  abdomen. 
Near  the  apex  comes  a  decided  break  where  the  sheaths  proper 
are  articulated.  These  are  long  and  slender,  equalling  the  ovi- 
positor in  length.  They  are  concaved  inwardly  and  convex 
with  ridged  rings  outwardly.  The  nota  of  the  eighth  and  ninth 
segments  are  small,  but  their  pleura  extend  backward  and  are 
overlapped  and  partially  concealed  by  those  of  the  seventh 
segment.  On  the  apex  of  the  ninth  segment  is  a  small,  blunt, 
rod-like  projection,  and  beneath  on  either  side  of  the  groove 
which  receives  the  sheaths  is  a  small  cercus.  Both  of  these 
parts  are  probably  tactile  in  their  nature. 

Sex  Distinction 

The  presence  or  absence  of  the  ovipositor  and  its  sheaths  is 
the  most  readily  noticed  sex  distinction,  but  there  are  others 
not  so  easily  noticed.  The  sternal  plates  of  the  female  are  longi- 
tudinally divided  and  the  small  projections  described  above 
are  usually  present,  while  in  the  males,  the  sternal  plates  are 
entire  and  the  projections  are  absent.  The  abdomen  of  the 
female  increases  in  size  towards  its  apex  while  that  of  the  male 
is  long,  slender,  and  approximately  of  the  same  width  throughout. 
The  small  rod-like  projections  on  the  ninth  segment  of  the  female 
are,  of  course,  lacking  in  the  male,  their  positions  being  occupied 
by  the  male  external  genital  organ.  The  ventral  cerci  of  the 
female  are  absent  in  the  male  but  the  male  has  a  pair  of  small 
cerci  on  the  dorsal  apex  of  the  eighth  segment  which  are  not 
found  in  the  female. 

Classification 

Tribe  Pimplini 

Ashmead,  Proc.  Ent.  Soc.  Wash.,  iii,  p.  278,  (1895). 
Schmiedeknecht,  Genera  Insectorum,  62nd  fascicle,  p.  18,  (1907). 

On  May  3,  1895,  Ashmead  read  a  paper  before  the  Entomolog- 
ical Society  of  Washington,  which  was  later  published  in  the 
Proceedings  of  that  society,  in  which  he  proposed  the  breaking 
up  of  the  sub-family  Pimplinae  into  a  number  of  tribes,  one  of 
which  was  to  be  called  Pimplini. 

TRANS.  AM.  ENT.  SOC,  XLI. 


124 


PIMPLINE  ICHNEUMONIDAE 


The  following  synoptic  table  leading  to  the  tribe  Pimplini  is 
taken  from  the  62nd  fascicle  of  the  Genera  Insectorum. 

1.  Head  more  or  less  cubical,  more  rarely  globular.    Mandibles  extended, 

and  with  the  clypeus  downwardly  bent  at  the  tip,  as  a  rule,  forming  the 
mouth  opening.   Antennae  and  legs  mostly  long  and  thin,  Tribe  Xoridini 
Head  transverse,  rarely  somewhat  elevated.    Mandibles  with  the  clypeus 
forming  no  apparent  mouth  opening..  .  2 

2.  Abdomen  depressed,  rarely  somewhat  compressed  at  the  tip.    The  last 

abdominal  segment  not  large.  Hind  legs,  particularly,  not  the  hind  coxae, 
neither  strikingly  long  nor  stout.    Antennae  almost  entirely  long  and 

slender  3 

Abdomen  behind  more  or  less  laterally  compressed.  The  last  ventral 
segment,  generally  plow-share  shaped  and  standing  out,  sometimes  very 
large,  lancet-shaped,  very  rarely  small  and  transverse.  Hind  legs  or 
at  least  hind  coxae  strongly  lengthened  and  generally  strongly  thickened. 

Antennae  more  or  less  short  and  stout,  

 (Tribes  not  included  in  this  paper) 

3.  Abdomen  with  more  or  less  distinct  impressions,  mostly  also  strongly 

punctured.  When  smoother  and  without  elevations,  then  segments 
2  to  5  have  deep  impressed,  obHque  lines  on  both  sides  which  converge 

toward  the  middle  of  the  base  Tribe  Pimplini 

Abdomen  without,  or  with  entirely  indistinct  impressions,  and  without 
coarse  sculpturing,  more  or  less  smooth  or  finely  punctured  or  leather- 
like Tribe  Lissonotini 

The  characters  of  the  tribe  Pimplini  are:  Head  transverse, 
rarely  somewhat  elevated.  Abdomen  depressed,  only  toward 
the  end  mostly  compressed,  with  more  or  less  distinct  impressions 
or  elevations,  usually  punctured,  rarely  smooth,  if  smooth 
alutaceous  or  coriaceous,  always  with  lateral  impressed  lines 
on  segments  2  to  5  which  converge  toward  the  middle  of  the 
base.  Mandibles  with  front  border  of  clypeus  not  forming  a 
mouth-opening.  Hind  legs  not  conspicuously  lengthened  and 
thickened. 

Synoptic  Table  to  Genera  Here  Treated 


Females 

1.  Mesonotum  transversely  rugose  2 

Mesonotum  not  transversely  rugose  (Genera  not  treated.) 

2.  Head  with  carina  between  the  antennae  Apechoneura 

Head  witlCa  carina  between  the  antennae.   3 

3.  Sternal  plates  of  abdomen  entire  Pseudorhyssa 


Sternal  plates  of  abdomen  divided  by  a  median-longitudinal  groove  4 


J.  H.  MERRILL 


125 


4.  Projections  along  groove  of  the  sternal  plate  nearer  the  base  of  each  seg- 


ment than  its  apex  Megarhyssa 

Projections  on  sternal  plate  situated  about  mid-way  between  base  and 
apex  of  each  segment  Rhyssa 

Males 

1.  Propodeum  areolated:  head  without  a  carina  between  the  antennae  

 Pseudorhyssa 

Propodeum  not  areolated  2 

2.  Pleura  and  sternum  of  second  abdominal  segment  fused  for  a  short  dis- 

tance   Megarhyssa 


Pleura  and  sternum  of  second  abdominal  segment  not  fused  Rhyssa 

Genus  MEGARHYSSA  Ashmead 

Thalessa  Holmgren,  Ofvers.  Svensk.  Vet.-Akad.  Forh.,  xvi,  1859,  p.  132. 

Megarhyssa  Ashmead,  Can.  Ent.,  xxxii,  1900,  p.  369. 

Megarhyssa  Dalla  Torre,  Cat.  Hym.,  iii,  1901-2,  p.  479. 

Thalessa  Schmiedeknecht,  Gen.  Ins.  Fasc.  62,  1907,  p.  63. 

Genotype:  {Ichneumon  clavator  Fabricius) .  [Sic]=  (Ichneumon)  Megarhyssa 
clavatus  (Fabricius)  =  (/c/inewmon)  Megarhyssa  Superbus  (Schrank).  (Vide 
Viereck,  Proc.  U.  S.  Nat.  Mus.,  Bull.  83,  p.  144,  (1914).) 

In  Megarhyssa  the  clypeus  is  usually  anteriorly  truncate,  the 
abdominal  segments  in  the  male  are  smooth,  with  segments 
3  to  7  at  the  apex  emarginate  or  deeply  excavated.  The  sternal 
plate  of  the  second  abdominal  segment  is  for  a  greater  or  lesser 
distance  fused  with  the  pleura  at  its  anterior  end.  The  amount 
of  fusion  varies  with  the  species.  The  sternal  plate  of  this 
segment  is  largely  membranous,  the  chitin  being  apparently 
degenerated.  Between  the  seventh  and  eighth  segments,  issues 
the  membrane  used  by  the  female  in  ovipositing,  as  already 
described.  The  projections  of  the  sternal  plates  of  segments 
3  to  6,  on  either  side  of  the  mid-ventral  groove  are  longer  than 
in  Rhyssa,  and  are  situated  nearer  the  base  than  the  apex  of 
each  segment. 

Table  to  Females 

1.  Insects  black  or  mostly  black  2 

Insects  yellow  or  yellowish  red  4 

2.  Black  with  white  spots  on  the  abdomen  humida  (Say)  (p.  126} 

Black  without  white  spots  on  the  abdomen  3 

3.  Ovipositor  at  least  twice  as  long  as  the  body  atrata  (Fabr.)  (p.  128) 

Ovipositor  not  twice  as  long  as  the  body  canadensis  (Cress.)  (p.  129) 

4.  Areolet  in  fore-wings  absent  mexicana  (Cress.)  (p.  131) 

Areolet  in  fore-wings  present  5 

TRANS.  AM.  ENT.  SOC,  XLI. 


126 


PIMPLINE  ICHNEUMONIDAE 


5.  Rounded  spots  on  the  sides  of  the  abdomen.  .  .nortonii  (Cress.)  (p.  131) 
No  rounded  spots  on  the  sides  of  the  abdomen  6 

6.  Yellow  band  behind  the  eyes  bordered  posteriorly  with  a  black  band. 

In  second  abdominal  s^egment,  pleura  and  sternum  fused  as  far  as  or 

but  slightly  beyond  the  spiracles,  wings  clouded  at  their  tips  

 lunator  (Fabr.)  (p.  133) 

Yellow  band  behind  the  eyes  not  bordered  posteriorly  with  a  black  band. 
Fusion  of  pleura  and  sternum  extending  twice  the  distance  from  base 
of  segment  to  spiracles,  ^ings  not  clouded  at  tips .  greenei  (Vier.)  (p.  136) 

Table  to  Males 

1.  Black  or  mostly  black  2 

Not  black  3 

2.  Abdomen  with  white  spots  on  its  sides  nitida  (Cress.)  (p.  137) 

Abdomen  without  white  spots  on  its  sides.  . .  .  canadensis  (Cress.)  (p.  129) 

3.  Recurrent  nervure  interstitial  with  outer  transverse  cubital  

 nortonii  (Cress.)  (p.  131) 

Recurrent  nervure  not  interstitial   4 

4.  Wings  fuscous  atrata  (Fabr.)  (p.  128) 

Wings  not  fuscous   5 

5.  Yellow  behind  the  eyes  bordered  by  a  black  band  extending  around  the 

head  nearly  to  the  mandibles,  wings  clouded  at  tips  

 lunator  (Fabr.)  (p.  133) 

Yellow  behind  the  eyes  merging  into  a  light  brown  band,  wings  not  clouded 
at  tips  greenei  (Vier.)  (p.  136) 

Megarhyssa  humida  (Say) 

Pimpla  humida  Say,  Boston  Journ.  Nat.  Hist.,  i,  pt.  3,  1836,  p.  224,  n.  1,  9  . 
Pimpla  humida  LeConte,  Writings  of  Thos.  Say,  ii,  1859,  p.  683. 
Rhyssa  humida  Dalla  Torre,  Cat.  Hym.,  iii,  1901-2,  p.  483. 

Type.  As  this  species  was  named  by  Say,  the  type  cannot  be 
located. 

The  female  of  this  species  is  about  half  an  inch  long  with  an  ovipositor 
slightly  longer  than  the  body.  The  head  is  yellowish-white  with  the  vertex 
and  a  broad  central  band  extending  to  the  base  of  the  insertion  of  the  antennae 
dark,  as  is  also  the  clypeus.  There  is  a  large  dark  spot  in  the  middle  of  the 
lower  margin  of  the  frons  from  which  a  dark  band  extends  to  the  antennae. 
The  mandibles  are  black  but  the  palpi  are  white.  The  antennae  are  brownish- 
black. 

A  broad  yellowish- white  band  extends  forward  along  the  upper  border  of  the 
prothorax  from  the  tegula  nearly  to  the  middle  line  in  front  and  downward 
at  its  posterior  end,  making  the  spot  somewhat  L-shaped.  Beneath  this  band 
is  a  broad  dark  band  running  parallel  to  it,  which  occupies  almost  all  of  the 
remaining  portion  of  the  prothorax.  Just  below  this  dark  band  and  above 
the  procoxa  is  a  pale  rufous  streak.  The  prosternum  is  pale  rufous.  The 
mesonotum  is  dark  as  is  the  prescutum.    This  dark  color  from  the  prescutum 


J.  H.  MERRILL 


127 


extends  backward  between  two  parallel,  longitudinal,  yellowish-white  bands 
on  the  mesonotum  to  the  mesoscutellum.  The  center  of  the  mesoscuteJlum 
has  a  square  yellowish-white  spot  on  it,  and  is  interrupted  at  its  front  margin 
by  a  dark  one.  The  posterior  margin  of  the  entire  plate  has  a  narrow  white 
line,  the  remainder  of  the  plate  is  black.  On  the  metascutellum  (generally 
called  postscutellum)  is  an  oblong  yellowish-white  spot.  Both  front  and 
rear  margins  of  this  plate  h'ave  a  yellowish-white  line,  each  side  is  black  and 
a  black  line  crosses  from  one  side  to  the  other  just  in  front  of  the  oblong  spot. 
The  mesosternum  and  metasternum  as  well  as  their  pleura  are  pale  rufous. 
The  tegula,  a  raised  spot  beneath  the  fore  wing  and  another  spot  below  this 
are  yellowish-white.  The  notum  of  the  propodeum  is  dark  with  a  yellowish- 
white  spot  separating  it  from  the  rufous  pleura  at  its  posterior  end.  The  legs 
are  pale  rufous,  with  the  knees,  tibiae  and  tarsi  whitish.  The  exterior  surface 
of  the  middle  tibiae  and  tarsi  as  well  as  the  tarsal  tips  and  sutures  are  darker. 
In  the  posterior  tibiae  the  outer  extremity  is  darkened  and  the  tarsal  segments 
become  darker  toward  the  tarsal  claws,  which  are  brownish-black.  The  wings 
are  hyaline  with  dark  brown  nervures.  The  stigma  is  pale  fuscous  at  its 
base  but  becomes  darker  towards  its  apex.  The  areolet  is  petiolated  and  the 
recurrent  nervure  enters  it  in  the  middle. 

The  abdomen  is  dark  brown,  poHshed  and  transversely  aciculated  above, 
and  obhquely  aciculated  at  the  sides.  On  the  notum  of  the  second  segment 
is  a  broad,  dorsal  depression  extending  from  the  base  nearly  to  its  tip.  On 
the  third,  fourth,  fifth,  sixth,  seventh  and  eighth  segments  are  roundish, 
yellowish-white  spots,  which  on  the  last  two  segments  become  elongated, 
with  their  axis  at  right  angles  to  that  of  the  body.  The  venter  is  yellowish- 
white  with  brown  bands.  The  ovipositor  is  of  a  reddish-brown  with  darker 
colored  sheaths. 

Male  unknown, 

Megarhyssa  humida  is  more  apt  to  be  confused  with  Rhyssa 
persuasoria  than  with  any  other  species,  yet  an  examination  of 
the  sternal  plates  will  show  a  marked  difference.  The  fact 
that  the  pleura  and  sternum  of  the  second  abdominal  segment 
are  fused  for  a  short  distance  will  serve  to  distinguish  it  from 
Rhyssa  persuasoria.  The  fact  that  the  mesosternum  and  meta- 
sternum of  M.  humida  are  rufous  and  not  black  is  another  dis- 
tinguishing character.  It  can  be  distinguished  from  M.  atrata 
by  the  absence  of  the  yellowish-white  markings  found  on  the 
latter.  It  can  be  distinguished  from  Megarhyssa  nortoniif 
canadensis,  lunator,  greenei,  and  mexicana  by  the  presence  of  its 
yellowish-white  orbits. 

This  species  was  described  by  Say  as  Pimpla  humida  and  was 
later  put  into  the  genus  Rhyssa  by  Walsh,  but  the  structural 
characters  of  the  sternal  plates,  the  fusion  of  the  pleura  and 
sternum  of  the  second  abdominal  segment,  the  ends  of  the 

TRANS.  AM.  ENT.  SOC,  XLI. 


128 


PIMPLINE  ICHNEUMONIDAE 


abdominal  segments  being  acute  instead  of  truncate,  would  seem 
to  place  it  in  Megarhyssa.  It  would  also  seem  that  this  might 
be  the  female  of  M.  nitida  on  account  of  the  similarity  of  color- 
markings,  size,  and  its  petiolated  areolet.    If  this  should  prove 

true  the  name  M.  nitida  would  fall  into  synonymy. 

« 

Megarhyssa  atrata  (Fabricius) 

Ichneumon  atrata  Fabricius,  Spec.  Insect.,  i,  1781,  p.  436. 

The  following  references  are  in  addition  to  those  given  by  Dalla  Torre: 

Lintner,  Country  Gentleman,  July,  1883,  p.  561. 

Harrington,  Can.  Ent.,  xix,  1887,  p.  206. 

Riley,  Insect  Life,  i,  1888-89,  p.  168  et  seq. 

Smith,  Insects  of  New  Jersey,  1909,  p.  627. 

This  species  varies  from  about  an  inch  to  an  inch  and  three-quarters  in 
length,  with  a  very  long,  dark-brown  ovipositor,  which  in  some  cases  attains  a 
length  of  five  or  six  inches.  The  head  and  antennae  are  yellow.  The  ocelli 
are  embedded  in  a  transverse  dark  band  extending  between  the  compound 
eyes.  There  is  another  transverse  dark  band  at  the  point  of  insertion  of  the  an- 
tennae, not  quite  reaching  the  compound  eyes,  and  a  black  spot  on  the  face  just 
above  the  clypeus.  The  ground  color  of  the  thorax  is  a  glossy  black  with  a 
yellow  spot  in  the  prothorax  just  in  front  of  the  fore  wing,  one  beneath  the  fore 
wing,  and  one  on  each  side  of  the  propodeum  near  where  it  articulates  with  the 
second  abdominal  segment.  On  each  side  of  the  mesoscutellum  is  a  short,  longi- 
tudinal dash,  while  in  the  center  of  the  metascutellum  (generally  called  post- 
scutellum)  is  a  transverse  yellow  dash.  The  legs  are  yellow  with  the  coxae, 
middle  and  hind  trochanters,  black  and  the  fore-trochanters  partly  yellow. 
The  procoxae  each  bear  a  more  or  less  indistinguishable  yellow  spot.  The 
middle  and  posterior  femora  are  black  with  yellow  tips.  The  tibiae  are  yellow, 
but  the  tarsal  segments  are  darker  at  their  outer  extremities  and  the  tips  of 
the  tarsal  claws  are  black.  The  wings  are  fusco-hyaline  and  show  an  irides- 
cence in  some  lights.  The  stigma  is  pale  ferruginous  at  its  base  becoming 
darker  toward  its  apex.  The  abdomen  is  brownish-black,  some  parts  being 
slightly  lighter  than  others. 

M.  atrata  may  be  distinguished  from  M. .  lunator,  greenei, 
and  mexicana  by  its  very  dark  abdomen.  Its  yellow  antennae 
will  distinguish  it  from  nitida,  canadensis,  and  humida.  Its 
larger  size  would  also  serve  to  distinguish  it  as  well  as  the  length 
of  the  ovipositor,  which  is  several  times  the  length  of  the  body. 

Its  life  history  is  similar  to  that  of  M.  lunator  and  M.  greenei 
with  which  it  is  commonly  found  associated.  The  dates  of  cap- 
ture of  specimens  seen  range  from  June  2  to  September  15. 

The  male  of  M.  atrata  differs  from  the  female  very  markedly 
in  its  color  markings.  The  structural  sex  differences  are  the 
same  in  M.  atrata  as  in  M.  lunator.    In  general  the  male  has 


J.   H.  MERRILL 


129 


more  yellow  upon,  it  than  the  female.  The  dark  spot  on  the 
face  just  above  the  clypeus  may  or  may  not  be  present.  The 
antennae  are  dark-brown  but  lighter  beneath  toward  their  tips. 
The  upper  margin  of  the  prothorax  is  marked  by  yellow  and 
this  color  may  in  some  instances  form  a  border  around  it,  leaving 
a  polished  black  spot  in  the  center.  Beneath  the  fore-wing  is 
a  raised  yellow  spot.  Just  below  it  and  extending  backward 
to  the  mesoepimeron  and  nearly  doAvn  to  the  sternum  is  a  yellow 
area.  This  area  may  be  partly  divided  into  two  by  a  darker 
stain  running  through  it.  The  prescutum  is  yellowish-brown 
and  from  it  two  bands  of  yellow  or  light  brown  pass  backward 
over  the  mesonotum  throughout  its  whole  length,  and  it  may  be 
also  more  or  less  completely  margined  by  the  same  color.  A  large 
yellow  spot  starts  on  each  side  of  the  metathorax  at  its  upper 
margin  and  extends  dorsally,  covering  the  pleura  of  the  propo- 
deum  and  nearly  meeting  the  other  on  the  notum.  Just  before 
the  hinder  margin  of  the  notum  of  the  second  and  sometimes 
of  the  third  abdominal  segment  is  a  narrow  transverse  yellow 
band.  The  rest  of  the  abdomen  is  brownish-black,  lighter  in 
spots.  M.  atrata  may  be  distinguished  from  lunator  by  the 
absence  of  clouded  areas  in  the  fore-wings,  from  M.  greenei  by 
its  fusco-hyaline  wings,  and  from  nortonii  by  receiving  the  recur- 
rent nervure  in  the  middle  of  the  areolet. 

Megarhyssa  canadensis  (Cresson) 

Rhyssa  canadensis  Cresson,  Can.  Ent.,  i,  1885,  p.  35,  9  ■ 

Location  of  type. — In  the  collection  of  the  American  Entomo- 
logical Society  of  Philadelphia. 

The  female  of  this  species  is  about  half  an  inch  long  with  an  ovipositor 
shghtly  longer  than  the  body.  The  head  is  dark  brown  to  black.  The  facial 
orbits  are  marked  with  a  yellowish-white  band  interrupted  at  the  point  of 
insertion  of  the  antennae  and  ending  at  the  vertex.  The  posterior  orbits 
in  the  hghter  colored  specimens  are  marked  by  a  lighter  brown.  The  palpi 
are  whitish.  The  dark  portion  below  the  antennae  is  shghtly  raised  medially 
and  the  whole  is  irregularly,  transversely,  striated.  The  antennae  are  dark 
brown  becoming  lighter  and  somewhat  larger  toward  their  tips. 

The  thorax  is  dark  brown  to  black  and  its  sides  are  clothed  with  numerous 
short,  erect,  whitish  hairs.  The  tegulae  are  yellowish-white.  The  meso- 
scutellum  and  metascutellum  (or  postscutellum)  are  transversely  striated. 
The  sides  of  the  thorax  are  highly  pohshed  and  in  the  mesothorax  are  densely 
punctured.    In  the  hghter  specimens  the  prothorax  is  marked  with  a  hghter 

TRANS.  AM.  ENT.  SOC,  XLI. 


130  PIMPLINE  ICHNEUMONIDAE 

brown  similar  to  that  of  the  posterior  orbits.  In  the  lighter  specimens  the 
rear  margin  of  the  mesoscutellum,  an  oblong  spot  in  the  centre  of  the  meta- 
scutellum  and  a  line  on  its  rear  margin  are  rufous.  In  the  darker  specimens 
these  plates  show  no  color  markings.  The  propodeum  is  transversely  striated 
above,  punctured  below,  with  a  median  longitudinal  depression  extending 
nearly  to  its  posterior  margin.  The  wings  are  fusco-hyaUne  tinged  with  yellow, 
and  slightly  more  fuscous  nervures  and  stigma  except  at  their  base  where 
they  are  Ughter.  The  areolet  is  small,  petiolated,  with  the  recurrent  nervure 
entering  at  its  middle.  The  legs  are  pale  rufous.  The  fifth  segment  of  the 
anterior  and  middle  tarsi,  and  the  claws  are  dark.  The  posterior  femur 
bears  a  dark  spot  at  its  extremity  as  does  the  tibia  near  its  base.  The  tibia  is 
darker  along  its  external  surface  completely  enveloping  its  outer  haK.  The 
posterior  tarsal  segments  are  darker  on  their  external  surface,  this  dark  color 
increasing  towards  the  claws,  which  are  all  dark. 

The  abdomen  is  dark  brown  to  black,  transversely  aciculated  above,  these 
aciculations  bending  forward  at  the  sides.  The  ovipositor  is  dark  brown 
with  darker  sheaths. 

The  male  of  this  species,  from  the  collection  of  the  U.  S.  National  Museum 
(here  described  for  the  first  time),  is  sUghtly  less  than  half  an  inch  long.  The 
head  is  black.  The  antennae  are  black  at  their  base  but  become  lighter  and 
somewhat  larger  toward  their  tips.  From  the  base  of  the  antennae  down 
to  the  clypeus  the  face  is  yellowish-white.  This  spot  is  prolonged  to  the  ver- 
tex in  the  form  of  bands  margining  the  compound  eyes. 

The  thorax  is  black  and  polished.  The  sides  of  the  mesothorax  and  meta- 
thorax  are  densely  punctured.  The  mesoscutellum  and  metascutellum  are 
transversely  striated.  The  propodeum  is  transversely  striated  except  along 
the  median,  longitudinal  depression,  which  extends  nearly  to  its  posterior 
margin.  Its  sides  are  punctured.  Numerous  short,  erect,  whitish  hairs  clothe 
the  thorax. 

The  wings,  legs  and  abdomen  are  as  in  the  female. 

In  size  and  general  appearance  M.  canadensis  resembles  humida 
more  closely  than  the  other  Megarhyssae  but  the  absence  of  white 
spots  on  the  side  of  the  abdomen  would  serve  to  distinguish 
it  from  humida  as  well  as  from  atrata.  Its  dark  brown  to  black 
color  with  whitish  color  markings  would  distinguish  it  from 
lunator,  greenei,  nortonii  and  mexicana. 

This  species  was  originally  described  by  Cresson  as  Rhyssa 
canadensis,  but  the  structure  of  its  sternal  plates,  the  fusion  of 
the  pleura  and  sternum  of  the  second  abdominal  segment,  and  the 
acutely  angled  tip  of  the  abdominal  segments  w^ould  seem  to 
place  it  in  Megarhyssa. 


J.  H.  MERRILL 


131 


Megarhyssa  mexicana  (Cresson) 
Epirhyssa  mexicana  Cresson,  Proc.  Acad.  Nat.  Sci.  Phila.,  1893,  p.  394,  9  • 

No  statement  about  the  types  accompanies  the  description, 
but  a  range  in  length  measurement  implies  that  more  than  one 
specimen  was  examined  and  there  are  two  specimens  labeled, 
''Type  No.  599,"  from  Mexico,  in  the  collection  of  the  American 
Entomological  Society  of  Philadelphia. 

9 .  This  species  is  about  an  inch  long,  with  an  ovipositor  a  little  longer 
than  the  body.  The  head  is  yellow  but  the  mandibles  are  black.  The  region 
in  which  the  ocelli  are  imbedded  and  extending  between  the  compound  eyes 
is  slightly  darker  than  the  ground  color  of  the  head.  Parallel  and  posterior 
to  this  darkened  area  is  a  dark  band  which  nearly  encircles  the  head.  The 
suture  from  the  compound  eyes  to  the  mandibles  and  extending  across  the 
upper  part  of  the  clypeus  is  also  dark.  The  antennae  are  dark  brown,  except 
the  under  side  of  the  scape  which  is  lighter  colored  than  the  flagellum. 

The  ground  color  of  the  thorax  is  pale  yellow.  The  sutures  separating  the 
mesonotum  from  the  prescutum,  prothorax  and  mesoscutellum  are  dark. 
A  dark  band  runs  along  the  center  of  the  prescutum  and  another  on  each  side 
of  the  mesonotum  runs  from  the  prescutum  back  to  the  mesoscutellum.  The 
suture  separating  the  mesothorax  from  the  metathorax  and  the  propodeum 
is  also  dark.  The  legs  are  yellow  and  the  tarsi  become  darker  toward  the 
tarsal  claws  which  are  dark  brown  or  black.  The  suture  dividing  the  posterior 
femur  from  its  trochanter  is  dark.  The  wings  are  faintly  yellow-hyaline, 
clouded  at  their  tips  and  without  an  areolet  in  the  specimens  examined. 

The  abdomen  is  yellow,  smooth,  and  gUstening.  The  tips  of  the  second, 
third,  fourth,  fifth  and  sixth  segments  are  each  bordered  with  a  black  band. 
In  the  remaining  segments  these  bands  are  nearly  obsolete.  The  ovipositor 
is  dark  brown. 

Male  unknown. 

Distinguishing  characters. — Mexicana  may  be  distinguished 
from  the  other  species  of  Megarhyssa  by  its  yellow  abdomen 
without  spots  and  probably  by  the  absence  of  the  areolet  in  its 
fore  wings. 

This  species  was  placed  in  Epirhyssa  by  Cresson,  but  the  struc- 
ture of  its  sternal  plates  agrees  with  those  of  Megarhyssa  and  the 
presence  of  the  areolet  seems  to  be  a  variable  character  in  thi? 
group. 

Megarhyssa  nortonii  (Cresson) 

Rhyssa  nortonii  Cresson,  Proc.  Ent.  Soc.  Phila.,  iii,  p.  317,  9 . 

Thalessa  quehecensis  Provancher,  Natural  Canad.,  v,  1873,  p.  317,  9  cf . 

Thalessa  nortonii  Provancher,  Faun.  Ent.  Canad.;  Hymen.,  1883,  p.  445. 

TRANS.  AM.  ENT.  SOC,  XLI. 


132 


PIMPLINE  ICHNEUMONIDAE 


Type. — In  the  collection  of  the  American  Entomological 
Society  of  Philadelphia. 

The  female  of  this  species  varies  from  about  an  inch  to  an  inch  and  a  half  in 
length,  with  an  ovipositor  about  twice  the  length  of  the  body.  The  head  is 
yellow,  marked  with  dark-brown  or  black.  There  is  a  dark  band  extending 
across  the  upper  part  of  the  head  between  the  front  margins  of  the  compound 
eyes,  in  which  the  ocelli  are  embedded.  From  this  dark  band  back  to  the 
occiput  extends  a  dark  brown  to  black  area,  slightly  lighter  in  color  than  the 
transverse  band.  From  the  latter,  a  dark  band  extends  down  to  the  labrum, 
where  it  broadens  out,  extending  to  the  lower  margins  of  the  compound  eyes, 
and  thence  downward  covering  all  of  the  lower  part  of  the  head  in  front. 
The  antennae  are  dark  brown  to  black  w^ith  the  scape  and  pedicel  more  glis- 
tening than  the  flagellum.  The  ground  color  of  the  thorax  varies  from  brown 
to  black.  There  is  a  yellow  spot  on  the  side  of  the  pro  thorax,  another  beneath 
the  wing,  on  the  side  of  the  metathorax,  and  on  the  propodeum  just  above. 
In  the  lighter  specimens  these  propodeal  spots  may  be  confluent  over  the 
dorsmn.  The  mesonotum  may  be  brown  with  black  markings,  black  with 
ferruginous  markings,  or  entirely  black.  The  mesoscutellum  has  a  square 
yeUow  spot  in  its  center  and  the  metascutellum  (generally  called  postscutellum) 
has  an  oblong  yellow  spot.  The  wings  are  hyaline,  tinged  with  yellow,  giving 
a  faint  violet  reflection  in  some  lights.  The  stigma  is  pale-ferrtiginous.  The 
legs  are  yellow  varying  with  darker  shades  of  the  same  color.  The  coxae 
vary  from  dark  brown  to  black.  The  middle  and  posterior  femora  are  dark 
with  their  tips  yellow,  as  are  also  the  tibiae.  The  tips  of  the  tarsal  claws  are 
black.  The  abdomen  is  sHghtly  hghter  in  color  than  the  thorax.  Just  before 
the  hinder  margin  of  the  notum  of  the  second  and  also  of  the  third  abdominal 
segments  is  a  small  transverse  yellow  band.  In  the  darker  colored  specimens, 
reddish-yellow  spots  are  found  on  the  sides  of  the  segments.  The  spots  on  the 
anterior  portion  of  the  abdomen  are  about  in  the  middle  of  each  segment, 
but  they  gradually  move  forward,  so  that  in  the  posterior  segments  they  are 
found  on  the  anterior  margins.  In  the  lighter  colored  specimens  they  are 
not  distinct  and  form  spots  only  a  little  lighter  than  their  surroundings.  On 
each  side  of  the  fourth,  fifth,  sixth,  seventh,  and  eighth  segments  is  a  yellow 
spot,  more  or  less  oval  in  form.  The  long  axis  of  the  spot  on  the  last  two 
segments  is  nearly  at  right  angles  to  the  body  axis. 

In  M.  nortonii  the  yellow  spots  on  the  sides  of  the  abdomen 
are  rounded-oval,  while  in  the  closely  related  M.  lunator  and 
M.  greenei  they  form  angled  bands.  In  M.  nortonii  there  is  a 
dark  stripe  extending  from  the  vertex  to  and  including  the  man- 
dibles, in  M.  lunator  there  are  two  dark  lines  running  from  the 
antennae  to  the  mandibles,  and  in  M.  greenei  these  lines  are 
absent.  M.  nortonii  can  be  distinguished  from  M.  mexicana 
in  that  the  latter  has  a  pale-yellow  ground  color,  ^with  black 
markings  on  the  abdomen.    The  wings  of  the  latter  are  clouded 


J.  H.  MERRILL 


133 


at  the  tips,  and  possess  no  areolet,  neither  are  there  any  dark 
markings  on  the  face.  M.  nortonii  may  be  distinguished  from 
M.  atrata,  humida,  canadensis  and  nitida  by  the  fact  that  in  these 
latter  forms  the  greater  part  of  the  surface  of  the  body  is  black, 
with  white,  yellow,  or  fuscous  body  markings. 

Megarhyssa  nortonii  is  widely  distributed  throughout  the 
United  States,  Canada,  and  Alaska.  Specimens  taken  from  the 
Pacific  coast  ranging  from  Alaska  down  through  California, 
exhibit  in  general  much  darker  color  markings  than  those  taken 
east  of  the  Rocky  Mountains. 

Provancher  described  M.  nortonii  as  Thalessa  quehecensis  in 
1873,  but  as  he  applied  the  identical  description  to  Thalessa 
nortonii  in  1883,  it  shows  that  he  recognized  that  the  two  were 
identical.  The  dates  of  capture  of  specimens  seen  range  from 
May  20  to  Aug.  7. 

Male.  Not  having  seen  what  he  would  consider  a  bona-fide 
specimen  of  a  male  nortonii,  the  writer  will  use  a  translation  of 
Provancher's  description  of  a  male.^ 

Male.  Length  one  and  one-tenth  inches.  Differ  little  from  the  female. 
The  polished  plaque  of  the  two  sides  of  the  prothorax  is  without  yellow  spots. 
The  metathorax  is  clearer  towards  its  extremity,  without  spots  on  the  sides 
and  flanks  are  of  a  uniform,  shiny  red.  Segments  one  and  two  have  a  yellow 
band  towards  the  summit.  The  second  segment  is  the  same  as  that  of  the 
female,  bordered  with  black  at  both  ends  and  on  the  sides.  The  recurrent 
nervure  is  interstitial  with  the  outer  transverse  cubital. 

Megarhyssa  lunator  (Fabricius) 

Ichneumon  lunator  Fabricius,  Spec.  Insect.,  i,  1781,  p.  430,  n.  64. 

The  following  references  are  additions  to  the  hst  given  by  Dalla  Torre: 

Lintner,  Country  Gentleman,  July  1883,  p.  561. 

Harrington,  Canadian  Entomologist,  xix,  1887,  p.  206. 

Riley,  Insect  Life,  i,  1888-89,  p.  168  et  seq. 

Smith,  Insects  of  New  Jersey,  1909,  p.  627. 

There  seems  to  be  no  record  of  the  present  location  of  the  type 
of  this  species. 

9 .  The  individuals  of  this  sex  vary  in  length  from  three-quarters  of  an 
inch  to  an  inch  and  a  half,  and  the  ovipositor  from  an  inch  and  a  half  to  three 
and  three-quarters  inches.  The  head  is  yellow  with  a  transverse  dark  band 
on  its  vertex,  in  which  are  inserted  the  three  ocelli.  Another  dark  band  behind 
the. former  and  running  parallel  to  it,  almost  encircles  the  head.  A  dark  line 
runs  from  the  base  of  each  antenna  to  the  labrum.  The  mandibles  are  dark 
brown,  stout  and  bidentate.    The  antennae  are  dark  brown  and  slender. 

*Le  Naturaliste  Canadien,  v,  1873,  p.  445. 

TRANS.  AM.  ENT.   SOC,  XLI. 


134 


PIMPLINE  ICHNEUMONIDAE 


The  ground  color  of  the  thorax  and  propodeum  is  yellow,  varying  somewhat 
in  shade  but  generally  rather  light.  The  markings  range  from  yellowish- 
brown  to  black  and  seem  in  some  places  to  be  situated  on  the  margin  of  the 
sclerites  to  quite  an  extent.  The  ground  color  of  the  legs  is  yellow,  like  the 
thorax,  becoming  darker  toward  the  tips.  Spots  and  streaks  of  brown  occur 
here  and  there. 

The  prescutum  which  is  practically  circular  in  outline  is  margined  with 
brown  or  black,  and  from  its  hinder  margin  a  band  of  this  color  extends  to 
the  hinder  end  of  the  mesoscutum  and  a  broader  band  narrowing  posteriorly, 
extends  backward  on  either  side.  The  ground  color  of  the  mesoscutum 
appears  as  a  pair  of  longitudinal  bands  and  a  narrow  margin  above  the 
tegula  at  each  side. 

In  the  fore  wing  there  is  a  brown,  sometimes  almost  blackish,  area  covering 
the  stigma  and  extending  backward  across  the  radial  cell,  the  tip  of  the  cubito- 
discoidal  cell  and  frequently  more  or  less  involving  the  areolet.  The  tip  of  the 
third  submarginal  cell  is  also  covered  by  a  spot  of  this  kind,  less  pronounced, 
however,  than  the  other. 

The  abdomen  is  brown,  varying  considerably  in  shade,  with  bands  and  hnes 
of  yellow.  Just  in  front  of  the  hinder  margin  of  the  notum  of  the  second  and 
also  of  the  third  segments  is  a  transverse  yellow  band,  slightly  bent  forward 
at  its  ends.  These  yellow  bands  in  the  lighter  forms  are  margined  with  browTi 
distinctly  darker  than  that  of  the  segments  as  a  whole.  In  the  darker  form 
these  margins  are  not  in  evidence  On  the  fourth,  fifth  and  sixth  segments, 
these  bands  are  extended  forward  almost  to  the  spiracles,  then  toward  the  hinder 
end  and  upward,  following  the  general  outline  of  the  end  of  the  segments, 
the  two  parts  of  the  band  forming  an  acute  angle.  These  bands  are  not  con- 
tinuous across  the  dorsimi,  nor  are  the  dark  bands  which  margin  them,  but 
in  the  eighth  segment  the  yellow  band  is  continuous. 

The  fusion  of  the  pleura  with  the  sternum  of  the  second  abdominal  segment 
extends  from  the  base  of  that  segment  out  to,  or  but  shghtly  beyond  the  spira- 
cles. 

The  male  lunator  differs  from  the  female  only  in  the  following  respects: 
the  abdomen  of  the  male  is  sub-cylindrical  throughout  and  not  plow-share 
shaped  as  in  the  female.  The  pleura  are  extended  downward  completely 
enveloping  the  sterna  of  aU  but  the  second,  third  and  a  smaU  portion  of  the 
fourth  segments.  The  sterna  are  not  longitudinally  divided  by  a  groove  and 
therefore  cannot  show  the  median-sternal  projections  which  may  be  seen  in 
the  female.  There  is  more  variation  in  the  color  markings  of  the  male,  some 
specimens  showing  a  dark  spot  on  the  face  above  the  clypeus:  just  before  the 
apex  of  the  second  and  also  of  the  third  abdominal  segments  is  a  short  trans- 
verse yellow  band,  shghtly  notched  at  the  center  of  its  inner  margin.  These 
bands  are  the  only  color  markings  on  the  abdomen.  This  sex  may  be  distin- 
guished from  the  male  atrata  by  the  spotted  wings,  and  from  nortonii  by  the 
recurrent  nervure  entering  at  the  middle  of  the  areolet. 

Distinguishing  Characters. — Lunator  may  be  distinguished  from 
greenei  by  the  following  differences.  It  has  dark  lines  from  the 
base  of  the  antennae  to  the  labrum,  a  dark  band  parallel  to  the 


J.  H.  MERRILL 


135 


one  in  which  the  ocelU  are  imbedded,  dark  patches  on  the  tips 
of  its  wings,  which  characters  are  absent  in  greenei.  In  lunator 
the  fusion  of  the  pleura  with  the  sternum  of  the  second  abdominal 
segment  extends  to  or  but  slightly  beyond  the  spiracle,  while 
in  greenei  it  extends  as  far  beyond  the  spiracle  as  the  distance 
between  the  spiracle  and  base  of  the  segment.  In  lunator  the 
dark  bands  on  the  abdominal  segments  are  not  continuous 
over  the  dorsum,  while  they  are  in  greenei.  On  the  eighth  seg- 
ment of  lunator  the  yellow  band  is  continuous  but  this  condition 
does  not  occur  in  greenei.  In  lunator  the  ovipositors  are  relatively 
longer  than  in  greenei,  being  from  two  to  two  and  a  half  times 
the  length  of  the  body,  and  in  greenei  from  one  to  one  and  a 
half  times. 

Lunator  may  be  distinguished  from  nortonii  by  the  shape  of . 
the  markings  on  the  4th,  5th  and  6th  abdominal  segments. 
In  lunator  they  are  acutely  angulated  bands,  while  in  nortonii 
they  are  roundish  spots.  The  wings  of  lunator  are  hyaline,  with 
dark  spots,  while  in  nortonii  they  are  transparent,  fuscous  and 
with  no  dark  patches.  It  can  be  distinguished  from  mexicana 
in  that  the  latter  is  bright  yellow  marked  with  black.  The 
apical  margins  of  the  abdominal  segments  of  mexicana  are  bor- 
dered with  black  bands  continuous  over  the  dorsum.  The 
areolet  of  the  fore  wings  of  mexicana  is  absent.  It  also  has  a 
dark  patch  on  the  tip  of  the  fore  wing  but  none  in  the  region  of 
the  stigma.  Mexicana  has  no  dark  lines  from  the  base  of  the 
antennae  to  the  labrum. 

Lunator  may  be  distinguished  from  atrata,  humida,  canadensis 
and  nitida  by  the  fact  that  in  these  forms  the  greater  part  of 
the  surface  of  the  body  is  black  with  white,  yellow  or  fuscous 
body  markings. 

This  species  is  widely  distributed  throughout  the  United 
States  and  Canada.  It  is  found  in  abundance  on  trees  and  logs 
which  are  infested  with  Tremex,  working  in  company  with  M. 
atrata  and  M.  greenei.  They  appear  early  in  the  summer  and 
throughout  the  whole  season  may  be  seen  crawling  about,  seeking 
a  favorable  spot  for  ovipositions.  After  laying  its  egg  the  insect 
is  often  unable  to  extricate  its  ovipositor  and  is  held  a  prisoner 
by  it  until  death.  Mr.  C.  W.  Johnson,  Curator  of  the  Boston 
Society  of  Natural  History,  observed  a  large  number  of  males 

TRANS.  AM.  ENT.  SOC,  XLI. 


136 


PIMPLINE  ICHNEUMONIDAE 


massed  together  on  a  log  in  Maine.  He  attempted  to  cap- 
ture them  with  his  net,  but  they  all  flew  away.  Returning 
to  the  same  spot  later,  he  found  the  males  again  assembled  there. 
This  time  he  reached  out  and  caught  a  number  with  his  hand. 
Upon  being  examined  they  were  found  to  be  males  of  both 
M.  lunator  and  M.  greenei.  The  female,  which  later  emerged, 
proved  to  be  a  specimen  of  M.  lunator.  Whether  there  was  a 
female  of  M.  greenei  about  to  emerge  near  where  the  M.  lunator 
came  out,  or  whether  the  males  are  unable  to  know  in  advance, 
the  species  to  which  the  emerging  insect  belongs,  is  a  question. 

The  dates  of  capture  of  the  specimens  of  this  species  which 
have  come  under  my  observation  range  from  May  13  to  Sep- 
tember 30,  although  these  are  very  probably  not  the  outside 
limits. 

Megarhyssa  greenei  Viereck 

Megarhyssa  greenei  Viereck,  Proc.  U.  S.  Nat.  Mus.,  xl,  p.  191,  $  cf. 
Smith,  Insects  of  New  Jersey,  1909,  p.  627. 
Viereck,  Proc.  Ent.  Soc.  Wash.,  xiii,  no.  2,  p.  96. 

Type.— Cat.  No.  13,499,  U.  S.  N.  M. 

Type  locality:  Harrisburg,  Pennsylvania;  female,  June  25, 
male,  August  22,  1908. 

Megarhyssa  greenei  agrees  with  M.  lunator  except  in  the 
following  details.  It  has  no  dark  lines  extending  from  the 
base  of  the  antennae  to  the  labrum.  The  band  parallel  to 
the  one  in  which  the  ocelli  are  imbedded,  which  in  M.  lunator 
i^  dark  brown  or  black,  in  M.  greenei  is  but  slightly  darker 
than  the  yellow  ground  color  of  the  head.  There  is  no 
dark  patch  on  the  tip  of  the  wings.  The  fusion  of  the  sternum 
and  pleura  extends  about  twice  as  far  from  the  base  of  the  second 
abdominal  segment  as  it  does  in  M.  lunator,  reaching  as  far 
beyond  the  spiracles  as  the  distance  from  the  base  of  the  segment 
to  the  spiracles.  On  the  abdomen,  the  black  bands  which  border 
the  yellow  markings  are  continuous  over  the  dorsum,  but  the 
yellow  band  on  the  eighth  segment  is  not  continuous.  The  ovi- 
positors are  relatively  shorter,  being  only  from  one  to  one  and 
a  half  times  the  length  of  the  body. 

The  description  of  M.  lunator  applies  to  the  male  of  M.  greenei 
in  all  respects  except  those  named  above. 

For  characters  distinguishing  this  species  from  others  in  the 
same  genus,  see  list  of  distinguishing  characters  given  after 
the  description  of  M.  lunator. 


J.  H.  MERRILL 


137 


The  dates  of  capture  of  specimens  seen,  range  from  June  2 
to  September  25. 

The  male  of  M.  greenei  differs  from  the  female  greenei  in  the 
same  respects  as  found  in  lunator,  although  the  color  markings 
more  closely  resemble  each  other  in  the  two  sexes  than  in  lunator. 
It  may  be  distinguished  from  the  male  of  lunator  by  the  absence 
of  the  clouded  spots  in  the  wing. 

Megarhyssa  nitida  (Cresson) 

Rhyssa  nitida  Cresson,  Proc.  Ent.  Soc.  Phila.,  iii,  p.  319,  cf  • 

Type. — There  is  one  type  specimen  from  Virginia,  in  the 

collection  of  the  American  Entomological  Society  of  Philadelphia. 

The  male  of  this  species  is  about  half  an  inch  long.  The  head  is  black. 
The  antennae  are  dark,  the  scape  is  yellowish-white  beneath,  and  the  fiagellum 
becomes  Hghter  towards  its  tip.  The  mandibles  are  black  but  the  palpi  are 
yellowish-white.  The  clypeus  is  yellowish-white  and  this  color  extends 
upwards  over  the  face,  spreading  to  the  compound  eyes;  to  the  base  of  the  in- 
sertion of  the  antennae  where  it  is  interrupted,  and  sometimes  to  the  vertex, 
as  two  yellowish-white  bands  margining  the  compound  eyes.  Behind  the 
compound  eyes  are  yellowish  white  bands,  stopping  just  short  of  the  mandibles 
and  the  vertex.  The  thorax  is  black.  Beginning  at  the  tegula  a  triangular 
shaped  white  band,  which  later  becomes  reduced  to  a  line,  passes  forward 
along  the  upper  border  of  the  prothorax  nearly  to  ics  middle  line.  A  white 
•  streak  appears  just  above  the  procoxa.  The  prescutum  and  mesonotum  are 
black,  the  latter  with  a  pair  of  fine  longitudinal  yellowish-white  lines  near 
its  center.  The  center  of  the  mesoscutellum  has  a  large  yellowish-white 
spot  on  it,  nearly  divided  at  its  front  margin  by  a  dark  one.  The  posterior 
margin  of  the  entire  plate  has  a  narrow  white  line.  On  the  metascutellum 
(postscutellum)  is  an  oblong  white  spot.  The  rear  margin  of  the  plate  bears 
a  yellowish-white  line.  The  tegulae  and  a  raised  spot  beneath  the  fore  wing 
are  yellowish-white .  The  metapleurae  are  pale  rufous .  The  wings  are  hyaline, 
iridescent,  with  fuscous  nervures  which  are  pale  at  their  base.  The  stigma 
is  fuscous  except  its  base,  which  is  pale.  The  areolet  is  small  and  petiolated. 
The  anterior  legs  are  yellowish-white,  on  the  outer  side  of  the  tibiae  are  slightly 
darker  markings.  The  extremities  of  the  tarsal  segments  are  darker  than 
their  bases  and  the  claws  are  dark.  The  middle  coxae  are  pale  rufous,  the 
trochanters,  femora,  tibiae,  and  tarsi  are  yellowish-white.  The  tip  and  a 
spot  at  the  base  of  the  femora  are  dark.  The  extremities  of  the  tarsal  claws 
are  much  darker  than  in  the  anterior  legs,  the  last  four  segtnents  being  almost 
completely  dark,  as  are  the  tarsal  claws.  The  posterior  coxae  are  pale  rufous, 
the  trochanters  are  yellowish-white,  with  their  extremities  dark.  The  femora 
are  rufous  with  a  dark  spot  on  their  outer  extremities.  The  tibiae  are  lighter 
but  each  has  a  dark  spot  on  its  extremity,  and  another  fainter  one  near  its 
base.  The  first  two  tarsal  segments  are  yellowish-white,  their  tips  dark,  the 
third,  fourth,  and  fifth  are  dark,  the  claws  are  rufous.    The  abdomen  is  black 

TRANS.  AM.  ENT.  SOC,  XLI. 


138 


PIMPLINE  ICHNEUMONIDAE 


and  polished.    On  each  side  of  the  third  segment  is  a  small  yellowish-white 
spot:  similar  spots  are  found  on  the  remaining  segments,  increasing  in  size 
up  to  the  fifth,  after  which  they  decrease. 
9  Unknown. 

M.  nitida  may  be  distinguished  from  the  rest  of  the  Megar- 
hyssae  by  means  of  its  dark  abdomen  with  the  yellowish-white 
markings. 

In  all  probability  M.  nitida  is  the  male  form  of  M.  humida  as 
previously  stated. 

Habits  of  Megarhyssa 

The  following  extracts  are  taken  from  an  article  by  C.  V. 
Riley, ^  because  he  gives  the  best  description  of  the  habits  of 
Megarhyssa. 

...  In  preparing  for  the  act  (oviposition)  the  position 
is  generally  longitudinal  or  in  a  line  with  the  axis  of  the  trunk  or 
branch,  the  head  either  up  or  down.  With  the  abdomen  raised 
in  the  air  the  ovipositor  is  taken  and  managed  with  the  hind  legs, 
and  the  tip  guided  by  the  front  tarsi.  The  two  outer  sheaths 
are  used  as  props  and  do  not  enter  the  wood  with  the  ovipositor 
proper.  They  are  generally  crossed — a  position  which  gives 
additional  strength  and  security  to  them.  Now,  by  a  movement 
from  side  to  side,  and  by  arching  the  abdomen  and  bearing  upon 
the  ovipositor  she  gradually  forces  this  back  through  the  tip 
of  the  abdomen  into  a  membrane  which  issues  from  between 
the  sixth  and  seventh  joints  dorsally.  There  is  a  wonderful 
muscular  power  in  the  anal  joints,  and  the  ovipositor  is  forced 
back  until  it  forms  a  perfect  coil,  so  that  when  the  abdomen  is 
stretched  in  a  straight  line  to  its  utmost  the  ovipositor  within 
the  membrane  makes  a  circle  almost  as  large  as  a  quarter  of  a 
dollar,  the  anal  joint  having  made  a  three-fourths  turn  within 
the  membrane.  In  this  manner  the  ovipositor  under  the  venter 
has  been  sufficiently  shortened  to  bring  its  tip  against  the  bark. 
During  this  operation,  however,  the  outer  sheaths,  which  have 
not  followed  the  ovipositor  within  the  membrane,  have  been 
obliged  to  make  a  more  or  less  irregular  coil  opposite  to  and  in 
front  of  the  membrane  on  the  ventral  side.  Now  commences 
the  operation  of  boring,  and  with  the  wonderful  muscular  power 
in  the  anal  joint  and  the  elasticity  of  the  membrane,  the  insertion 
of  the  ovipositor  goes  on  quite  steadily  if  the  wood  be  in  the 
9  Insect  Life,  i,  1888-89,  p.  168. 


J.  H.  MERRILL 


139 


least  soft.  As  the  borer  enters,  the  sheaths  make  a  larger  and 
larger  loop  on  one  side  of  the  body,  or  even  a  valve  on  each  side. 
,  .  .  In  withdrawing  the  ovipositor  the  reverse  action  takes 
place  and  the  loops  of  the  outer  sheaths  gradually  become 
smaller  and  smaller;  the  ovipositor  is  again  forced  back  into  the 
tough  bladder-like  membrane  between  the  sixth  and  seventh 
joints  dorsally  and  we  have  a  repetition  of  the  appearance." 

The  old  idea  was  that  the  Megarhyssa  probed  a  burrow  with 
her  ovipositor  until  she  came  in  contact  with  the  larva  of  a 

9 

Tremex,  which  she  pierced  and  deposited  an  egg  therein.  The 
observation  has  also  been  made  that  the  insect  is  lignivorous  and 
not  parasitic.  Both  of  these  conclusions  have  been  shown  to 
be  false.    Riley  quotes  J.  A.  Lintner/^  as  follows: 

.  .  In  all  instances  where  I  have  found  the  female 
depositing,  it  has  been  in  trees  infested  with  Tremex  columha^ 
and  I  have  found  her  more  numerous  on  badly  affected  or  injured 
trees,  or  even  on  stumps  or  broken  trunks  already  partly  decayed. 
The  instinct  to  reach  the  egg  or  larva  of  Tremex,  so  dwelt  upon 
in  popular  accounts,  is  imaginary.  She  bores  directly  through 
the  outer  parts  of  the  tree,  and  doubtless  probes  for  a  burrow; 
but  her  egg  is  consigned  anywhere  in  the  burrow;  the  young  larva 
seeks  its  prey,  and  lives  and  develops  without  penetrating  the 
body  of  its  victim,  but  fastened  to  the  exterior.  This  habit 
among  parasites  is  much  more  common  than  is  generally  sup- 
posed. A  great  many  Rhyssa  (i.e.  Megarhyssa)  larvae  doubtless 
perish  without  finding  food,  and  a  great  many  females  die  in 
probing  for  a  burrow,  especially^when  they  burrow  through  wood 
that  is  sound  and  hard. " 

In  this  same  paper,  Riley  in  speaking  of  some  personal  observa- 
tions, says,  ".  .  .  We  examined  the  burrows  very  carefully 
and  found  Thalessa  (i.  e.  Megarhyssa)  in  all  stages  at  that  time — 
larvae,  pupae  of  both  sexes,  and  imagines  of  both  sexes  within 
the  tree — the  larvae  being  of  various  sizes  and  invariably  external 
to  the  Tremex:  i.  e.  not  within,  but  holding  on  to  its  victim  and 
sucking  the  latter's  life  away,  without  in  any  case  entering  the 
body." 

The  insect  remains  within  the  tree  until  it  becomes  adult,  then 
it  gnaws  its  way  to  the  surface  and  escapes.    The  males  usually 
10  Country  Gentleman,  xlix,  1884,  p.  331. 

TRANS.  AM.  ENT.   SOC,  XLI. 


140 


PIMPLINE  ICHNEUMONIDAE 


appear  first.  W.  H.  Harrington  has  given  a  series  of  obser- 
vations made  in  June,  1887,  in  which  he  showed  that  the  males 
having  issued  first,  awaited  the  females,  and  were  able  to  locate 
the  spot  at  which  a  given  female  would  emerge,  some  time  before 
she  made  her  appearance.  In  one  instance  which  he  records, 
a  particular  spot  was  crowded  with  males  for  two  days  before 
the  female  emerged,  and  even  then,  she  was  assisted  by  the 
removal  of  the  bark  by  the  observer.  The  males,  in  waiting, 
make  every  effort  to  reach  the  female,  inserting  the  tips  of  their 
abdomen  into  crevices  in  the  bark.  On  emerging  the  female 
is  instantly  seized,  the  legs  of  the  male  clasping  the  yet  unused 
wings  and  abdomen,  thus  preventing  her  from  flying. 

Genus  RHYSSA  Gravenhorst 

Rhyssa  Gravenhorst,  Ichneum.  Europ.,  ill,  1829,  p.  260. 
Epirhyssa  Cresson,  Proc.  Ent.  Soc.  Phila.,  iv,  1865,  p.  39. 
Pararhyssa  Walsh,  Trans.  Acad.  Sci.  St.  Louis,  v,  1873,  p.  109. 
Rhyssa  Riley,  Ins.  Life,  i,  1888-9,  p.  169  (habits). 
Rhyssa  Dalla  Torre,  Cat.  Hym.,  iii,  1901-2,  p.  482. 
Epirhyssa  Schmiedeknecht,  Gen.  Ins.,  fasc.  62,  1907,  p.  59. 
Rhyssa  Schmiedeknecht,  Gen.  Ins.,  fasc.  62,  1907,  p.  62. 
.  Rhyssa  Ramsey,  The  Entom.,  xlvii,  1914,  p.  20  (habits). 

Genotype:  Ichneumon  persuasorius  Linn. 

Rhyssa,  a  primitive  and  widespread  genus,  occurs  both  in 
America  and  Europe.  In  North  America  it  is  found  from 
Alaska  to  Mexico  and  from  the  Pacific  to  the  Atlantic  coast, 
and  is  also  found  on  the  island  of  Cuba.  There  are  two  records 
of  fossil  Rhyssae  being  found,  one  in  the  Lower  Miocene  and  the 
other  in  the  Oligocene.^^  It  occurs  under  such  a  variety  of 
climates  and  conditions  that  considerable  variation  both  in 
color  and  structural  characters  is  found.  It  would  seem  as  though 
it  were  trying  to  break  up  into  a  number  of  races  and  thence 
to  species,  but  its  variations  have  not  become  fixed  to  such  an 
extent  that  they  may  be  considered  as  permanent.  Rhyssa 
persuasoria,  the  oldest  described  species  of  this  genus,  was  de- 
scribed by  Linnaeus;  since  there  have  been  several  new  species 
described,  in  some  instances  from  a  single  specimen,  but  the 
amount  of  variation  is  so  great  that  it  does  not  seem  safe  to 
accept  as  a  new  species,  one  described  from  a  single  specimen. 


11  Can.  Ent.  xix,  1887,  p.  206. 

12  Scudder,  Tert.  Insect,  t.  10,  1890,  p.  19. 


J.  H.  MERRILL 


141 


In  1804,  Cresson  described  Rhyssa  alhomaculata.  He  separated 
this  species  from  R.  persuasoria  on  the  grounds  that  the  former 
had  a  white  band  on  its  antennae,  a  slight  difference  in  color 
markings  and  a  small  petiolated  areolet,  but  as  specimens  occur 
with  white  banded  antennae  and  areolets  similar  to  those  with 
black  antennae  and  vice  versa,  and  as  there  is  a  great  range  in 
both  thoracic  and  abdominal  markings  which  do  not  adhere 
always  to  the  antennal  or  areolet  differences,  it  would  seem  that 
R.  alhomaculata  is  really  R.  persuasoria.  R.  skinneri  Viereck 
is  described  from  one  specimen,  mainly  upon  structural  characters, 
with  some  difference  in  color  markings,  but  in  R.  persuasoria 
there  is  a  marked  variability  in  structural  as  well  as  in  color 
markings.  The  clypeus  may  range  from  pointed  to  truncate, 
the  face  may  be  medially  elevated  and  smooth  or  striated  or 
the  whole  face  may  be  elevated.  There  is  considerable  variation 
in  the  puncturing  and  rugulose  characters  of  the  thorax.  The 
notum  of  the  propodeum  may  or  may  not  have  a  medial-longi- 
tudinal depression.  As  for  the  differences  in  color  it  would 
seem  that  no  dependence  could  be  placed  upon  them,  and  that 
Rhyssa  skinneri  will  probably  prove  to  be  a  synonym.  Rhyssa 
alaskensis  was  described  by  Ashmead  from  one  specimen.  The 
description  of  this  species  will  apply  equally  well  to  Rhyssa 
persuasoria  and  it  will  probably  prove  to  belong  to  the  latter 
species. 

Table  to  Species  of  Rhyssa 

1.  Face  elevation  longitudinally  rugulose  skinneri  Viereck 

2.  Face  elevation  not  longitudinally  rugulose  persuasoria  Linnaeus 

Rhyssa  skinneri  Viereck 

Rhyssa  skinneri  Viereck,  Trans.  Am.  Ent.  Soc,  xxix,  1903,  p.  87,  9 . 

Type. — In  collection  of  Acad,  of  Nat.  Sci.  Phila.,  from  Beulah, 
New  Mexico,  Aug.  17,  1901,  (H.  Skinner). 

"Face  rugulose;  mesonotum  almost  uniformly  transversely  striate,  the 
striae  not  apparently  gibbose.  Raised  line  separating  metanotum  and  pleura 
poorly  defined,  being  obsolete  below  the  spiracles.  Length,  23  mm.,  face 
somewhat  elevated  medially,  the  elevation  rather  longitudinally  rugulose, 
sides  and  anterior  margins  of  the  face,  pohshed  and  moderately  sparsely  punc- 
tured. Clypeus  highly  poHshed,  distinctly  produced  to  a  point  medially,  and 
with  a  row  of  deep  punctures.  Cheeks  pohshed,  almost  impunctate.  Dor- 
sulum  transversely  striate,  the  striae  delicate  but  well  defined  posteriorly. 

TRANS.  AM.  ENT.  SOC,  XLI. 


142 


PIMPLINE  ICHNEUMONIDAE 


Carina  on  anterior  half  of  mesopleura  becoming  indistinct  half  way  upon  the 
pleura,  strongly  striato-punctate,  the  superior  half,  highly  poUshed.  Scutellum 
flattened,  transversely  striate.  Metanotum  with  a  slight  median  longitudinal 
impression,  delicately,  transversely  sculptured,  laterally  shining,  rugulose;  me- 
tapleura  polished,  sparsely  punctured,  rugulose  on  the  superior  margin.  Wings 
hyaline,  with  a  brown  cast,  nervures  and  stigma  dark  brown,  second  recurrent 
nervure  interstitial  with  the  second  transverse  cubitus.  Dorsal  abdominal 
segments  finely  transversely  sculptured,  having  a  satiny  luster.  Ovipositor 
about  29  mm.  in  length.  Black,  a  line  from  malar  space  to  apex  of  the  eye, 
a  band  on  the  superior  border  of  the  propleurae,  a  spot  below  on  the  tubercle, 
a  spot  on  the  anterior  coxae,  greater  part  of  the  tegulae,  a  large  spot  beneath, 
a  small  spot  on  the  mesopleurae,  a  spot  on  the  medial  coxae,  a  short  line  to 
the  sides  and  apex  of  first,  second,  third,  fourth,  fifth  and  sixth,  and  a  lateral 
line  on  the  seventh  dorsal  segments,  white.  Greater  part  of  four  anterior 
legs  (excluding  coxae)  ochraceous.  Apex  of  first,  all  of  second  trochanters  and 
the  femora  of  posterior  legs  ferruginous;  the  tibiae  and  tarsi  dark  brown. 
Described  from  one  female  specimen  ''closely  related  to  R.  persuasoria  but 
distinguished  by  the  difference  in  sculpture,  very  distinct  in  coloration." 

As  the  writer  has  never  seen  the  type  of  this  species,  the  original 
description  by  Viereck  is  here  given. 

Rhyssa  persuasoria  (Linnaeus) 

Ichneumon  persuasoria  Linnaeus,  Syst.  Nat.,  Ed.  x,  1758,  p.  256,  n.  67. 
Cryptocentrum  lineolatum  Kirby,  Fauna  Bor.  Amer.,  iv,  1837,  p.  260. 
Rhyssa  albomaculata  Cresson,  Proc.  Ent.  Soc.  Phila.,  iii,  1864,  p.  318. 
Rhyssa  (Pararhyssa)  albimaculata  Walsh,  Trans.  Acad.  St.  Louis,  iii,  1873, 
p. 109. 

Cryptocentrum  lineolatum  Kirby,  Can.  Ent.,  ix,  1877,  p.  150. 

Epirhyssa  crevieri  Provancher,  Nat.  Canad.,  xii,  1880,  p.  17. 

Rhyssa  persuasoria  Riley,  Insect  Life,  i,  1888-89,  p.  169. 

Rhyssa  albomaculata  Hopkins,  Bull.  32,  West  Va.  Exp.  Sta.,  1893,  p.  217. 

Rhyssa  persuasoria  Morley,  The  Entomologist,  xlii,  1909,  p.  133,  note. 

Rhyssa  persuasoria  Morley,  The  Entomologist,  xliii,  1910,  p.  243. 

Rhyssa  alaskensis  Ashmead,  Harr.  Alaska  Exp.,  ix,  1910,  p.  205. 

Type. — Location  unknown.  Type  of  Cryptocentrum  lineo- 
latum in  British  Museum. 

The  female  of  this  species  is  from  about  half  an  inch  to  nearly  an  inch  in 
length.  Its  color  markings  are  also  very  variable.  The  head  is  dark  brown 
to  black.  In  most  instances  the  orbits  of  the  compound  eyes  are  white, 
rarely  interrupted  at  the  vertex,  and  extending  downward  as  far  as  the  clypeus 
on  each  side  of  the  eye.  In  some  specimens  there  is  a  white  band  just  above 
the  clypeus  connecting  the  lower  ends  of  the  bands  of  the  facial  orbits,  in 
others  the  lower  part  of  the  face  below  the  antennae  and  above  the  clypeus 
is  white.  The  clypeus  may  be  pointed  or  vary  toward  truncate.  Below  the 
antennae  the  face  may  be  raised  centrally  or  entirely,  and  its  surface  may  be 


J.  H.  MERRILL 


143 


smooth  or  striated.  The  antennae  are  dark  brown  to  black.  Some  are  all 
black,  some  have  a  suggestion  of  white,  some  one  or  two  segments  that  are 
white,  while  in  others  there  may  be  a  number  of  distinct,  white  segments 
forming  a  band  on  the  antennae.  The  individuals  having  this  last-named 
characteristic  have  been  regarded  by  some  as  forming  a  separate  species, 
Rhyssa  alhomnculata. 

The  thorax  is  dark  brown  to  black.  There  is  a  variable  amount  of  thoracic 
punctures  and  striations.  The  prothorax  is  bordered  above  and  below  with 
a  varying  amount  of  white.  In  some  the  sides  of  the  prothorax  have  such  an 
amount  of  white  that  the  dark  ground  color  only  shows  as  a  spot  in  the  center. 
The  mesonotum  is  immaculate.  On  the  center  of  the  mesoscutellum  is  a 
square  white  spot,  and  usually  there  is  a  white  line  on  the  rear  margin  of  the 
entire  plate.  There  is  an  oblong  white  spot  on  the  center  of  the  metascutellum 
(postscutellum)  and  this  plate  may  or  may  not  have  its  rear  margin  marked 
by  a  white  line.  The  tegulae  and  a  raised  spot  beneath  the  fore  wings  are 
always  white.  On  the  mesopleuron  just  below  the  attachment  of  hind  wing 
is  a  white  spot  and  another  just  above  and  in  front  of  the  middle  coxae.  The 
size  of  these  spots  is  variable  and  they  may  even  coalesce,  margining  the  post- 
erior border  of  the  mesopleuron.  There  is  a  variable  white  spot  on  the  side 
of  the  metathorax  and  another  just  above  it  on  the  propodeum.  In  some 
specimens  there  is  a  median  longitudinal  depression  on  the  notum  of  the  pro- 
podeum; in  others  it  is  suggested,  while  in  some  it  is  absent.  The  wings  are 
hyaline  sometimes  tinged  with  yellow.  The  nervures  and  stigma  are  fuscous 
except  at  their  base,  where  they  are  paler.  The  shape,  size,  and  even  the  pres- 
ence of  the  areolet  are  variable.  The  recurrent  nervure  is  usually  interstitial 
with  the  outer  transverse  cubital  nervure.  In  some  the  latter  nervure  is 
present  and  assists  in  forming  the  areolet,  in  others  but  a  stub  of  it  remains 
while  in  some  cases  it  is  absent.  In  some  cases  the  areolet  is  petiolated, 
receiving  the  recurrent  nervure  in  its  middle.  The  legs  vary  from  light  yellow 
to  rufous,  the  coxae  from  white  to  black  with  white  spots.  In  general  the 
posterior  legs  are  darker  than  the  others.  The  color  is  even  more  variable 
in  the  legs  than  in  the  thorax.  The  abdomen  is  dark  brown  to  black,  lustrous, 
and  finely,  transversely  aciculated  above.  The  lower  borders  of  the  pleura 
of  the  second  segment  are  each  margined  with  a  white  band,  which  bends 
upward  at  its  posterior  margin  and  usually  meets  its  fellow  of  the  opposite 
side,  above.  The  third  segment  is  similarly  marked  except  that  the  bands  do 
not  quite  meet  above.  Usually  on  the  fourth,  fifth,  sixth,  and  seventh  seg- 
ments these  bands  are  interrupted  so  that  a  spot  is  formed  on  the  upper 
side  of  the  pleuron,  while  its  lower  border  remains  marked  with  a  white  band. 
In  some,  the  spot  and  band  are  connected  on  the  seventh  segment.  On  the 
last  segment  the  white  marking  is  continuous  along  the  posterior  margin  but 
does  not  meet  its  fellow  above.  This  line  is  not  always  continuous.  The 
ovipositor  is  shghtly  longer  than  the  body,  dark  brown  to  black,  with  darker 
colored  sheaths. 

The  male  differs  from  the  female  in  that  the  face  below  the  antennae  ia 
whiter  and  the  anterior  coxae  and  femora  are  lighter  colored. 


TRANS.  AM.  ENl.  SOC,  XLI. 


144 


PIMPLINE  ICHNEUMONIDAE 


I  have  not  seen  the  type  of  Rhyssa  shinneri  Viereck,  as  already 
stated,  but  from  the  description,  it  does  not  seem  impossible 
that  it  may  be  a  form  of  this  species. 

Habits  of  Rhyssa 

The  Rhyssae  by  means  of  their  ovipositors  bore  into  trees 
infested  with  borers  and  there  deposit  their  eggs.  They  are 
primary  parasites  on  Sir  ex,  Monohammus  and  Urocerus  cyaneus. 
As  their  life  from  hatching  to  adult  is  spent  within  the  trunks 
of  trees,  it  has  made  a  study  of  their  history  practically  impossible. 
It  has  been  generally  assumed  that  they  were  external  parasites, 
but  H.  J.  Erne  gives  an  account  of  raising  Rhyssa  from  Sirex, 
According  to  him  the  eggs  were  laid  within  the  larvae.  It  has 
been  clearly  shown  that  in  the  closely  related  genus  Megarhyssa, 
the  eggs  are  external  to  the  larvae.  The  tip  of  the  ovipositor 
is  constructed  for  sawing  into  wood  and  not  for  piercing  other 
insects.  It  does  not  seem  probable  that  the  members  of  one 
genus  live  as  external  while  those  of  so  similar  a  genus  should  live 
as  internal  parasites.  Yet  the  only  published  evidence  that  has 
been  found  asserts  that  Rhyssa  live  as  internal  parasites.  Erne's 
observations  will  be  given  here  though  their  accuracy  is  doubted. 

''In  studying  Serropalpus  I  had  an  opportunity  to  observe 
Pimpla  persuasoria.  The  eggs  of  Pimpla  were  usually  laid  in 
the  larva  of  a  species  of  Sirex,  which  were  very  inactive  on  that 
account,  and  did  not  put  up  any  resistance.  After  they  hatched 
the  little  larva  remained  in  the  Sirex  larva  until  the  latter  died. 
The  larva  of  Pimpla  had  by  this  time  attained  a  size  of  two  or 
three  lines. 

''They  left  the  Sirex  larva  after  it  was  dead,  and  from  time 
to  time  fed  on  the  remains.  If  the  Sirex  larva  is  large  the  Pimpla 
larva  has  food  enough,  but  if  it  is  small,  the  food  supply  is  not 
sufficient,  and  since  the  Pimpla  does  not  try  any  other  nourish- 
ment it  dies  in  the  wood.  Frequently  the  Sirex  larva  with  the 
parasite  larva  in  its  body,  penetrates  deeply  into  the  wood,  so 
that  the  developed  Pimpla  has  to  bite  its  way  out  of  the  wood 
from  a  depth  of  two  lines  in  order  to  get  free.  For  a  space  of 
three  days  it  thus  works  itself  forward;  if  it  does  not  get  free 
in  three  days  its  strength  becomes  weakened  and  it  dies  in  the 

13  Mittheil.  Schweiz.  Entom.  Gesell.,  iv,  1876,  p.  9,  p.  518. 


J.  II.  MERRILL 


145 


wood.  If  one  would  rear  the  larva  of  a  Pimpla  persuasoria,  one 
must  give  it  the  remains  of  the  same  larva  for  nourishment  in 
which  it  was  hatched.'' 

Riley  says  that  Ratzeburg  states  that  both  Nordlinger  and 
himself  raised  Rhyssa  persuasoria  from  Sirex  spectrum,  but  does 
not  give  any  details  of  his  observations  nor  does  he  state  that 
the  parasite  in  ovipositing  pierces  the  wood-boring  grub. 

The  subject  of  the  habits  of  Rhyssa  is  by  no  means  a  clear 
one,  and  it  awaits  some  worker  who  will  be  fortunate  enough 
to  observe  its  complete  life  history. 

The  genus  Rhyssa  Gravenhorst,  has  its  clypeus  medially 
lengthened  or  unidentate  and  its  abdominal  segments  rounded 
at  the  apices.  The  sternal  plate  of  the  second  abdominal 
segment  is  not  fused  with  the  pleura.  The  projections  of  the 
sternal  plates  on  either  side  of  the  mid-ventral  groove  are  placed 
about  mid-way  between  the  base  and  apex  of  each  segment. 
The  sternal  plate  of  the  second  abdominal  segment  is  composed 
almost  wholly  of  chitin.  The  ovipositors  of  Rhyssa  are  but 
little  longer  than  the  body,  consequently  they  do  not  need  the 
membrane  which  is  used  by  Megarhyssa  in  forcing  its  long  ovi- 
positor into  the  wood. 

Since  the  above  was  written  an  article  has  appeared  on  the 
habits  of  oviposition  by  Rhyssa  by  L.  N.  G.  Ramsay, as  follows: 

''The  remarkable  insects  of  the  genus  Rhyssa  have  for  long 
been  known  to  prey  on  the  wood-boring  larvae  of  Siricidae, 
introducing  their  eggs  into  the  tunnels  of  the  latter  by  means  of 
their  enormously  elongated  ovipositor.  The  ovipositor  is  some- 
times even  found  sticking  in  a  Sirex-iniested  log  (as,  for  example, 
the  specimens  exhibited  in  the  insect  gallery  at  South  Kensing- 
ton), but,  I  understand,  the  manner  in  which  the  insect  contrives 
to  insert  this  unwieldy  appliance  into  the  tree-trunk  has  not 
hitherto  been  fully  described.  I  hope,  therefore,  that  the  follow- 
ing account  may  be  of  interest  to  entomologists. 

''The  event  described  was  witnessed  in  the  summer  of  1909, 
while  I  was  staying  in  the  southern  part  of  the  Black  Forest, 
to  the  west  of  the  Wehratal.    On  the  afternoon  of  August  29th, 

14  Insect  Life,  i,  1888-89,  p.  169. 

«  The  Entomologist,  xlvii,  p.  20,  f.  14,  (1914). 


TRANS.  AM.  ENT.  SOC,  XLI. 


146 


PTMPLINE  ICHNEUMONIDAE 


while  skirting  a  wood — the  very  finest  conifers  of  the  Black 
Forest  flourish  in  this  locality — I  happened  to  pause  beside  a  pile 
of  small  pine  logs,  and  as  I  stood  there  one  of  these  extraordinary 
insects  appeared  and  settled  on  one  of  the  logs.  I  will  quote 
verbatim  from  my  notes  written  the  same  day: —  'It  sat  still  for 
some  time,  and  then  began  to  walk  about,  feeling  every  hole 
and  (p.  21)  corner  in  the  rough  bark  with  its  long  antennae. 
After  a  minute  or  two  of  this  it  stopped,  and  drew  up  its  long 
body,  doubling  the  long  black  ovipositor  underneath  itself; 
it  had  to  hitch  itself  up  several  times  before  it  got  the  long  needle 
into  position  underneath,  with  the  tip  in  a  crevice.  Then  it 
gripped  the  bark  with  its  claws  and  gradually  thrust  the  ovipositor 
about  half  an  inch  into  the  bark,  then  suddenly  flew  away,  per- 
haps because  it  had  completed  laying  the  eggs,  perhaps  because 
I  had  gone  too  close.    .    .  . 

''Immediately  after,  I  made  the  rough  sketches  of  the  beast 
which  accompany  this  note.  These  are  probably  a  little  larger 
than  life,  although  the  insect  was  a  very  large  one.  I  noted  that 
the  abdomen  was  black  and  white,  the  legs  pale,  and  the  antennae 
black. 

"At  the  time  I  was  unaware  of  the  insect's  identity,  but  on 
seeing  the  specimens  of  Rhyssa  exhibited  at  the  Natural  History 
Museum  this  year,  I  at  once  recognized  my  old  acquaintance, 
and  comparison  of  the  other  species  of  the  genus  in  the  cabinet 
collections  there  leaves  little,  if  any  doubt,  that  this  was  R. 
persuasoria. 

"The  figures  will  help  to  indicate  the  manner  in  which  the 
insect  succeeded  in  bringing  its  unwieldy  ovipositor  to  bear  on 
the  log.  As  mentioned  above,  these  were  drawn  before  I  left 
the  spot  (with  the  exception  of  the  second,  which  I  have  added 
now  to  make  the  action  clearer),  and  they  are  reproduced  without 
any  change  from  my  original  rough  drawings.  As  the  insect 
had  already  taken  its  departure,  they  are  necessarily  crude,  as 
it  was  the  only  example  of  its  kind  on  which  I  had  ever  set  eyes. 
For  this  and  for  their  obvious  artistic  defects  I  shall  make  no 
further  apology,  as  they  are  merely  intended  to  convey  the 
manner  in  which  the  insect  accomplished  its  object. 

Sharp    figures  (after  Riley)  the  allied  genus  Thalessa  (now 

Cambridge  Natural  History,  Insects,  pt.  i,  p.  554,  1895. 


J.   H.  MERRILL 


147 


Megarhyssa)  in  the  act  of  oviposition,  and  states  that  in  both 
these  genera  the  ovipositor  is  ''brought  into  use  by  being  bent 
on  itself  over  the  back  of  the  insect,  so  as  to  bring  the  tip  ver- 
tically down  onto  the  wood,  through  which  it  is  then  forced  by 
a  series  of  efforts;  the  sheaths  do  not  enter  the  wood. 

It  is  evident  that  this  description  does  not  tally  with  the 
foregoing  observations  on  Rhyssa.  The  insect  figured  by  Sharp 
follows  his  statements  in  having  its  long  ovipositor  bent  on  itself, 
out  of  its  normal  and  approximately  straight  form,  into  an  almost 
complete  circle.  From  purely  physical  considerations,  is  it  not 
a  little  difficult  to  understand  how  a  non-muscular  structure 
could  be  curved  at  will  in  this  way?  The  possibility  suggests 
itself  to  the  present  writer  that  the  insect  there  figured,  after 
having  inserted  its  ovipositor  in  the  manner  described  in  this 
note  for  Rhyssa,  may  have  pivoted  its  body  through  an  angle 
of  180°  around  the  flexible  fixed  ovipositor,  in  its  efforts  to  thrust 
the  latter  into  an  unusually  resistant  piece  of  wood.  This  might 
easily  happen  through  the  insect's  shifting  its  feet  again  and 
again  to  obtain  a  better  purchase,  and  would  explain  the  whole 
matter  very  simply,  as  the  ovipositor  in  such  a  case  would  natu- 
rally assume  the  position  figured. 

There  can  be  no  doubt  at  all  that  Mr.  Ramsay's  notes  refer 
to  R.  persuasoria  (Linnaeus),  which  has  an  extremely  wide  dis- 
tribution through  Europe  to  Canada  and  the  United  States  in 
the  West,  and  the  Himalayas  in  the  East,  since  it  is  to  the  best 
of  my  knowledge  the  only  species  attacking  phytophagous  larvae. 
R.  approximator  (Fabricius),  is  said  by  Holmgren  to  attack 
Xyphydria  prolongata,  which  feeds  in  oaks;  and  there  are  several 
interesting  accounts  of  the  American  species'  economy  and  Har- 
rington has^^  put  on  record  ''The  Nuptials  of  Thalessa. "  Mr. 
Ramsay  appears  to  take  it  for  granted  that  these  insects  bore 
for  themselves  an  egg-passage  through  the  solid  wood;  but  it  is 
by  no  means  proved  that  they  do  not  oftener  introduce  them 
along  the  tunnel  of  the  host  larva.^^ 

"  Canad.  Entom.,  xi,  1879,  p.  15  etc. 
"  L.  c.  xix,  p.  206. 

"  Cf.  Morley,  Ichn.  Brit.,  iii,  p.  25,  and  Revision  Ichn.  Brit.  Mus.  ii,  p.  10. 

TRANS.  AM.  ENT.  SOC,  XLI. 


148 


PIMPLINE  ICHNEUMONIDAE 


Genus  APECHONEURA  Kreichbaumer 

Apechoneura  Kreichbaumer,  Ann.  Naturh.  Mus.  Wien,  v,  1890,  p.  485. 
Apechoneura  Schmiedeknecht,  Genera  Insectorum,  Fasc.  62,  1907,  p.  60. 
Apechoneura  Morley,  Rev.  Ichneumon  Brit.  Mus.,  ii,  1913,  pp.  3,  22,  23. 

Genotype:  Rhyssa  terminalis  BruUe. 

The  head  is  square  with  a  distinct  carina  between  the  antennae. 
The  antennae  are  long  and  filiform.  The  mesonotum  is  trans- 
versely rugose.  The  propodeum  is  distinctly  areolated  anteriorly, 
but  posteriorly  is  less  distinctly  so.  The  transverse  median 
nervure  is  straight,  not  broken.  The  sub-discoidal  nervure  origi- 
nates from  the  median  vein  far  beyond  the  apex  of  the  sub-median 
cell.  The  areolet  in  the  fore-wing  is  trapezoidal  or  three  cor- 
nered, sessile,  or  shortly  petiolated.  The  abdomen  is  long  and 
cylindrical,  with  an  ovipositor  as  long  or  longer  than  the  body. 
The  largest  species  usually  have  a  dark  spot  in  the  tip  of  the 
wing. 

Table  to  Species 

This  table  is  taken  from  Morley's  Revision  of  Ichneumonidae, 
Part  II.  The  types  of  these  two  species  are  in  the  British  Mu- 
seum, and  therefore  Mr.  Morley  has  had  an  opportunity  to  ex- 
amine them.  Not  having  seen  Mocsary's  paper  I  am  unable 
to  include  his  species. 

Abdomen  with  only  a  discal  line  black  nigritarsis  Cameron 

Abdomen  black  and  flavous,  not  at  all  red  carinifrons  Cameron 

Apechoneura  nigritarsis  (Cameron) 

Rhyssa  nigritarsis  Cameron,  Biol.  Cent.-Am.,  Hymen.,  i,  1886,  p.  260,  9  . 
Rhyssa  nigritarsis  Schmiedeknecht,  Gen.  Ins.,  Fasc.  62,  1907,  p.  63. 
Apechoneura  nigritarsis  Morley,  Rev.  Ichneumon.,  ii,  1913,  p.  23. 

Type. — In  the  British  Museum. 

"Fulvo  testacea;  antennis,  mesonoto  (medio-excepto),  linea  metanoti, 
abdomine,  supra  tarsisque,  nigris;  alis  hyaline,  apice  fumata.  Habitat, 
Panama,  Volcan  de  Chiriqui  at  2000-4000  ft. 

"Length  22  mm.  Antennae  nearly  as  long  as  the  body,  stout,  gradually 
thickened  towards  the  apex;  the  base  testaceous  on  the  lower  side.  Head, 
if  anything,  broader  than  the  mesothorax,  the  face  strongly  punctured,  the 
clypeus  obscurely,  transversely,  striated,  with  two  deep  shining  black  depres- 
sions above  the  antennae,  separated  by  a  thin,  rather  sharp  partition,  vertex 
punctured  in  front,  laterally  behind  the  ocelli  aciculated;  mandible's  black 

20  Ann.  Mus.  Nat.  Hungar.,  iii,  1905. 


J.  H.  MERRILL 


149 


at  the  apex.  Pronotum  reaching  to  near  the  top  of  the  head,  rising  rather 
perpendicularly  in  front;  the  mesonotum  projects  a  little  over  it,  and  rises 
from  the  scutelliim  to  the  apex,  which  has  a  distinct  margin;  the  margin  pro- 
jects upward  in  the  center  and  is  depressed  in  the  middle.  Mesonotum 
transversely  striated  as  usual  and  with  a  longitudinal  furrow  on  each  side  of 
the  apical  three-fourths,  scutellum  shining,  obscurely  punctured,  broader 
than  long,  slightly  narrower  towards  the  apex.  Pleurae  shining,  obscurely 
punctured,  a  longish  longitudinal  hollow  in  the  middle.  The  mesonotum  is 
black  except  laterally  in  front  and  down  the  center.  Scutellum  testaceous, 
the  sutures  black.  There  is  a  longish  black  mark  under  the  fore-wings; 
the  base  and  apex  of  the  metanotum,  and  a  broad  line  down  its  center  are 
black.  The  longish  curved  spiracles  are  bordered  with  black.  Metanotum 
shining,  impunctate,  a  curved  transverse  keel  runs  across  its  center  and  an 
obhque  one  from  the  spiracles  to  the  apex.  Abdomen  shining,  somewhat  com- 
pressed, black  above,  the  apex  pilose,  in  the  center  of  the  penultimate  segment 
is  a  somewhat  triangular  depression,  covered  with  a  white  membrane;  the 
last  segment  above  foims  a  projecting  thickly  pilose  lobe;  on  the  lower  side 
it  projects  more  and  ends  in  two  horny  processes  which  clasp  the  ovipositor. 
Ovipositor  nearly  three  times  longer  than  the  body,  white  at  the  apex.  Legs 
shining,  the  hind  coxae  black  at  the  base  on  the  lower  side.  Areolet  large, 
triangular,  receiving  the  recurrent  nervure  in  the  middle."  Original  descrip- 
tion from  Cameron. 

Apechoneura  carinifrons  (Cameron) 

Rhyssa  carinifrons  Cameron,  Biol.  Cent.-Am.,  Hymen.,  i,  1886,  p.  261,  9  cf . 
Apechoneura  carinifrons  Schmiedeknecht,  Gen.  Ins.,  Fasc.  62,  1907,  p.  60. 
Apechoneura  carinifrons  Morley,  Rev.  Ichneumon.,  ii,  1913,  p.  24. 

Type. — In  the  British  Museum. 

"Testacea,  nigro  varia,  antennis  nigris,  medio  apicique  subtus  testaceis; 
pedibus  rufo-testaceis;  basis  et  apice  coxarum  posticarum,  apice  femorum, 
dimidio  apicali  tibiarum  posticarum  tarsisque,  nigris;  alis  hyaUne,  apice 
fumato.    Habitat,  Nicaragua. 

"Antennae  as  long  as  the  body,  the  base,  the  middle  narrowly  and  the  apex 
(except  the  extreme  point),  testaceous  on  the  lower  side.  Face  transversely 
punctured,  the  vertex  impunctate,  a  distinct  keel  (separating  the  antennal 
depression)  runs  down  from  the  ocelli  to  a  little  below  the  base  of  the  antennae; 
eyes  margined,  especially  on  the  inner  side  and  above;  testaceous,  the  mandi- 
bles, the  antennal  depressions,  a  broad  transverse  band  on  the  vertex  enclosing 
the  ocelli  and  the  hind  region,  black.  Thorax  formed  as  in  nigritarsis, 
testaceous;  the  mesonotum  (except  a  broad  mark  on  the  center),  the  sutures, 
the  base  of  the  metanotum  broadly,  the  sides  of  the  prothorax  in  front,  a 
large  mark  on  the  mesopleura,  and  the  metapleura  close  to  the  sternum,  black. 
In  the  center  of  the  metanotum  two  short  keels  run  from  the  transverse  keel, 
forming  a  somewhat  square  area.  Abdomen  black;  the  ventral  surface,  a 
longish  mark  at  the  base  of  the  first  segment  in  the  center,  its  apex  and  the 
apices  of  the  other  segments  broadly  testaceous.    The  middle  coxae  are  black 

TRANS.  AM.  ENT.   SOC,  XLI. 


150 


PIMPLINE  ICHNEUMONIDAE 


beneath,  the  hind  coxae  are  black  on  the  lower  side  at  the  base  and  bear  a 
longer  black  mark  on  the  apex  above,  on  the  inner  side  they  are  entirely 
black  except  a  small  testaceous  spot;  the  hind  femora  are  infuscate  toward 
the  apex,  and  more  than  the  apical  hah  of  the  hind  tibiae  is  black,  tarsi  black, 
testaceous  in  the  middle.  What  appears  to  be  the  male  from  Panama  differs 
from  the  specimens  from  Nicaragua  in  having  a  broad  white  band  on  the 
antennae  close  to  the  apex  and  the  yellow  on  the  head  and  legs  brighter  in 
tint;  there  is  no  black  on  the  coxae  nor  are  the  hind  femora  infuscate  toward 
the  apex;  the  black  on  the  hind  is  only  on  the  outer  side;  and  the  abdomen 
is  broadly  dilated  laterally  at  the  apex." 

This  species  was  originally  described  by  Cameron  as  Rhyssa 
carinifrons  but  in  the  Genera  Insectorum  it  is  placed  in  Apecho- 
neura,  probably  on  account  of  the  carina  between  the  antennae 
and  its  areolated  propodeum. 

Genus  PSEUDORHYSSA  new  genus 
Genotpye:  Pseudorhyssa  sternata  new  species. 

This  genus  is  characterized  by  its  abdominal  sterna  being 
entire  instead  of  being  separated  by  a  median  longitudinal  groove. 
It  has  an  areolated  propodeum  consisting  of  three  areas.  The 
nota  of  the  second  and  third  abdominal  segments  are  laterally 
bordered  with  a  ridge  forming  a  depression,  which  is  not  found  in 
the  other  Pimplini  genera  which  have  the  transversely  rugose 
mesonotum.    There  is  no  carina  between  the  antennae. 

Pseudorhyssa  sternata  new  species 

Type:   9  ;  Toronto,  Ontario,  Canada.   August  20,  1892.  Col- 
lection of  the  American  Entomological  Society,  Type  No.  4007. 
Six  paratypes  in  same  collection. 

The  females  of  this  species  range  from  three- quarters  of  an  inch  up  to  an 
inch  and  a  quarter  in  length.  The  head  is  black,  polished,  and  slightly  punc- 
tured. The  clypeus  varies  in  outline  from  unidentate  to  bidentate.  Below 
the  antennae  the  face  is  brown  marked  hy  two  parallel  longitudinal  yellow 
bands,  which  extend  from  the  base  of  the  antennae  to  the  clypeus.  On  the 
base  of  each  mandible  is  a  yellow  spot.  The  clypeus  is  rufous  at  its  base  and 
darker  at  its  tip.  The  palpi  are  yellowish- white  marked  with  black.  The 
antennae  are  dark  brown  to  black,  and  the  scape  has  a  yellow  spot  beneath. 
The  thorax  is  black  and  bears  a  number  of  short,  erect,  whitish  hairs.  The 
pronotum  is  deeply  excavated  on  both  sides,  highly  polished  and  almost 
impunctate.  The  first  thoracic  spiracle  is  bordered  with  yellow  and  this 
<;olor  may  extend  forward  for  a  short  distance  on  the  upper  border  of  the 
pronotum.  The  tegulae  are  yeUow.  The  mesonotum  is  flat  on  top  and  is 
separated  from  the  present um,  only  by  two  short  parallel  longitudinal  grooves 
along  its  anterior  portion.    Posteriorly  the  prescutum  is  continuous  with  the 


J.  H.  MERRILL 


151 


mesonotum,  the  transverse  rugulae  of  the  latter  passing  over  the  former  in  a 
continuous  line.    The  anterior  portion  of  the  prescutum  is  punctured. 

The  mcsopleura  are  smooth,  polished  on  their  superior  portions,  punctured 
and  clothed  with  short  white  hairs  on  their  inferior  portions.  A  short  groove 
extends  forward  on  the  mesopleura  from  the  mesoepimeron,  starting  at  a 
point  about  two-thirds  of  the  distance  from  its  base  to  its  apex.  The  meso- 
scutellum  and  metascutellum  are  smooth  on  their  sides,  with  oblique  to  longi- 
tudinal stria*ions,  their  centers  are  punctured  and  clothed  with  hairs.  The 
metathorax  is  smooth,  slightly  punctured  and  clothed  with  short,  white  hairs. 
The  propodeum  is  coarsely  punctured,  except  for  a  dorsal  area  enclosed  by 
ridges,  which  is  polished  and  but  sUghtly  punctured.  These  ridges  start  at, 
or  near  the  base  of  the  segment,  pass  posteriorly,  as  two  gradually  diverging 
straight  lines  for  about  two-thirds  its  length,  where  they  become  circularly 
dilated  to  such  an  extent,  that  at  their  posterior  extremities  they  reach  to 
the  lateral  margins  of  the  notum,  thus  forming  three  areolated  areas  on  the 
propodeum.  The  wings  are'  hyaline,  tinged  with  yellow,  the  nervures  and 
stigma  are  dark  -brown  except  at  their  base,  where  they  are  lighter.  The 
recurrent  nervure  is  interstitial  with  the  outer  transverse  cubitus.  The  legs 
are  rufous,  paler  beneath.  The  tarsal  segments  are  sometimes  darker  towards 
the  tarsal  claws,  which  are  also  dark.  The  posterior  femora  each  have  a 
dark  spot  on  its  extremity.  The  posterior  tarsi  are  darker  than  the  others. 
The  abdomen  is  coarsely  punctured  and  irregularly  wrinkled.  The  notum  of 
the  second  abdominal  segment  is  laterally  bordered  with  a  strong  ridge.  From 
each  anterior  extremity  of  the  notum  extends  a  ridge  to  its  apex.  These 
ridges  gradually  converge  and  enclose  a  median  longitudinal  channel,  which 
at  its  base  is  poHshed  and  impunctate  but  becomes  coarsely  punctured 
and  irregularly  wrinkled.  From  this  depression  a  number  of  transverse 
wrinkles  extend  to  the  lateral  margins  of  the  notum.  The  pleura  of  this 
segment  are  coarsely  punctured  and  do  not  fuse  with  the  notum.  There  is  a 
small  obtusely  rounded  projection  on  the  outer  margin  of  the  segment  at  the 
point  where  the  ridges  end.  This  projection  is  bordered  by  a  rufous  streak. 
The  notum  of  the  third  segment  has  transversely  wrinkled,  oblique  depressions 
ext.ending  from  either  side  of  the  projecting  lobe  of  the  second  segment  out- 
ward to  the  lateral  margin  of  the  notum.  The  rest  of  the  notum  is  coarsely 
punctured  and  irregularly  wrinkled,  except  a  raised  portion  at  the  truncate, 
outer  margin  which  is  finely  punctured.  The  sternal  plates  are  not  divided 
by  a  median  longitudinal  groove,  consequently  there  are  no  mid-ventral 
projections.  This  segment,  as  are  also  the  fourth,  fifth,  and  sixth,  is  bordered 
with  a  rufous  band.  The  remaining  segments  are  coarsely  punctured  and 
irregularly  wrinkled  on  their  nota.  The  fifth,  sixth,  seventh  and  eighth 
segments  have  truncate  outer  margins  laterally,  with  slight  emarginations 
on  their  nota.  The  ovipositor  is  longer  than  the  body,  dark  brown  but 
lighter  at  its  tip,  with  darker  colored  sheaths. 

This  species  is  described  from  seven  specimens,  one  each  from 
''Maine,"  ''Colorado"  and  ''Toronto,  Canada,"  and  four  from 
"Washington  Territory. "    It  may  be  distinguished  from  Megar- 

TRANS.  AM.  ENT.  SOC,  XLI. 


152 


PIMPLINE  ICHNEUMONIDAE 


hyssa,  Rhyssa,  and  Epirhyssa  by  its  entire  abdominal  sterna, 
areolated  propodeum,  and  by  the  excavations  on  the  nota  of  the 
second  and  third  abdominal  segments,  and  may  be  distinguished 
from  Apechoneura  by  the  absence  of  a  carina  between  its  antennae. 

Unlocated  Species 

Thalessa  ?  histrio  Kreichbaumer 

Thalessa?  histrio  Kriechbaumer,  Ann.  Naturh.  Hof-Mus.,  Wien.,  v,  p. 
487,  d". 

''Head,  thorax,  and  feet  black,  varied  with  rufo-flavous,  abdomen  rufous, 
base  black  segments  1  and  2  banded,  3  on  both  sides,  apical  spots  flavous. 
Wings  hyahne,  stigma  flavous,  this  sunken  triangular  spot  and  apex  of  the 
wings  fuscous,  areola  wanting.  Length,  13  mm.  Because  of  the  absence  of 
the  areola  perhaps  forming  a  proper  genus,  which  I  have  omitted  to  estabUsh 
since  the  female  as  yet  unknown  might  fail  to  show  the  very  imperfect  charac- 
teristic marks.  Head  flavous,  apex  of  mandibles,  eyes,  occipital  bands  be- 
neath on  both  sides  reddish,  ocellar  region,  the  line  on  the  vertex  joined  with 
it,  and  antennae  black,  of  this  the  first  two  segments  beneath,  the  upper  line 
and  two  facial  sutures  rufous.  Thorax  black,  nearly  the  whole  margin  of 
the  anterior  pleura,  pronotum,  two  longitudinal  striae  and  tw^o  punctures 
before  the  mesonotum,  striae  below  the  wings,  tegulae,  scutellum,  postscutel- 
lum,  three  lateral  metathoracic  spots,  tip  of  dorsum  near  place  of  junction, 
slightly  golden-yellow.  Nearly  the  whole  of  the  anterior  coxae,  the  posterior 
above  and  on  the  sides  flavous,  summit  angulated  and  below  fuscous,  anterior 
trochanter  flavous,  dark  punctured,  posterior  ones  fuscous,  top  flavous  or 
rufous,  hind  part  more  or  less  fulvous,  in  front  flavous,  above  rufous,  bended, 
on  both  sides,  posteriorly  below  fuscous  lined,  posterior  rufous,  top  flavous, 
anterior  tibiae  and  tarsi  flavous,  posterior  rufous,  base  of  exterior  radial  nervure 
of  wing  irregularly  bent.  Forceps  on  the  last  anal  segment  short  on  top, 
summit  triangularly  greatly  impressed,  setrments  straight.  Ends  of  segments 
abruptly  truncated. 

Habitat:  White  Mountains." 


J.  H.  MERRILL 


153 


EXPLANATION  OF  PLATES 

Plate  XII 

Fig.  1. — Antenna  of  Megarhyssa  lunator. 

Fig.  2. — Maxilla  of  Megarhyssa  lunator. 
C — cardo.  G — galea.    L — lacinia.    P — palpus.    S — stipes. 

Fig.  3. — Head  of  Megarhyssa  lunator. 

CE — compound  eye.    CL — clypeus.    GE — gena.    L — labrum.    MD  — 
mandible. 

Fig.  4. — Mandible  of  Megarhyssa  lunator. 

Fig.  5. — Dorsal  view  of  thorax  of  Megarhyssa  lunator. 

Fig.  6. — Lateral  view  of  thorax  of  Megarhyssa  lunator. 

a2 — second  abdominal  segment,  cxl — procoxa.  cx2 — mesocoxa.  cx3 — 
metacoxa.  epm2 — mesocpimcron.  epmS — metaepimeron.  epsl — proepi- 
sternum.  eps2 — mesoepisternum.  cps3 — mctaepisternum.  nl — pronotum. 
ppct2 — prepectus.  psc2 — prescutum.  sp — spiracle.  scl2 — mesoscutellum. 
scl3 — metascutellum.  sct2 — mesoscutum.  sct3 — metascutum.  tg — tegula. 
tsp — thoracic  spiracle. 

Plate  XIII 

Fig.  1. — Abdomen  of  Megarhyssa  lunator. 

Fig.  2. — Sternal  plate  of  abdomen  of  Megarhyssa. 

Fig.  3. — Sternal  plate  of  abdomen  of  Rhyssa. 

Fig.  4. — Second  abdominal  segment  of  Rhyssa. 

Fig.  5. — Second  abdominal  segment  of  Megarhyssa. 

Fig.  6. — Hind  leg  of  Megarhyssa  lunator. 

Fig.  7. — Fore  leg  of  Megarhyssa  lunator. 

Plate  XIV 

Fig.  1. — Fore  wing  of  Megarhyssa  lunator  according  to  Snodgrass. 

1 — costal  vein.  2 — sub-costal  vein.  3 — radial  vein.  4 — median  or  ex- 
terno-median  vein.  5 — anal,  sub-median  or  interno-median  vein.  7 — basal 
vein.  9 — cubital  vein.  11 — transverse  cubital  vein.  12 — transverse  cubital 
vein.  13 — transverse  medial  vein.  14 — discoidal  vein.  15 — subdiscoidal 
vein.    16 — first  recurrent  vein.    17 — second  recurrent  vein.    19 — stigma. 

Fig.  2 — Fore  wing  of  Megarhyssa  lunator  according  to  Cresson, 

a — costal  and  sub-costal  nervures  blended,  b — externo-medial  nervure. 
c — anal  nervure.  d — basal  nervure.  e — marginal  or  radial  nervure.  f — 
first  transverse  cubital  nervure.  g — second  transverse  cubital  nervure. 
h — transverse  medial  nervure.  i — abbreviated  cubital  or  stump  of  nervure. 
j — discoidal  nervure.  k — cubital  nervure.  1 — recurrent  nervure.  m — sub- 
discoidal nervure.  n — stigma. 


TRANS.  AM.  ENT.  SOC,  XLI. 


154 


PIMPLINE  ICHNEUMONIDAE 


Fig.  3. — Hind  wing  of  Megarhyssa  lunator. 

a — costal  nervure.  b — sub-costal  nervure.  c — externo-medial  nervure. 
d — anal  nervure.  e — marginal  or  radial  nervure.  g — discoidal  nervure. 
h — transverse  medial  nervure.    i — transverse  cubital  nervure. 

Fig.  4 — Fore  wing  of  Megarhyssa  lunator. 

Fig.  5 — Hind  wing  of  Megarhyssa  lunator. 

a — anal,  c — costa.  d — cu.  cubitus,  r — radius.  sc — sub-costa.  m — 
medius. 


Trans.  Am.  Ent.  Soc,  Vol.  XLI. 


ri.  xii. 


epni2  PSCI3 


^sp  sch    sctj  sc/j  psch 


/scti 

'2  ^  epmj 

MERRILL— PIMPLINE  ICHNEUMONIDAE 


Trans.  Am.  Ent.  Soc,  Vol.  XLl. 


PI.  XIII. 


MERRILL  — PIMPLINE  ICHNEUMONIDAE 


Trans.  Am.  Ent.  Soc,  Vol.  XLI. 


5 

MERRILL  — PIMPLINE  ICHNEUMONIDAE 


I 


